I read your original post, but it is difficult to guess, what the problem is. Some more information could be helpful. Did you try if channel 19 and 20 send their signals through the faders to mains? And what happens if you send channel 19 to aux 2? Is the mute button on channel 19 ok (nothing sticking in it / keeping it down or up)? Is there anything else "funny" on channels 17 to 24? These channels belong together "internally".

Sometimes a factory reset can "heal" that kind of problems/hickups. Save what you want to keep and do it…!

If that doesn't help the board probably needs a repair. I once had the problem with my old SL 2442 that one fader was defect in the area above 0 dB, which caused black outs of that channel and peaks in high frequencies.

The new SL's faders have a much better protection against dust and dirt, so this might be your problem.

Thanks, I'll try the idea of assigning it to the main and see if it is muted into that route as well.
It seems to me like its a firmware problem, it stores the scene as if the mute button for channel 19 is on even though it is not. I have to over ride the stored value by muting and then unmuting. What if I store the scene without the state of the mutes enabled? and just allow the current state of the mute buttons to control it? And no I do not think there is anything wrong with the button/switch itself, it is not sticking.

Files (scenes) can get corrupted. This can happen for example if you shut down the board during its automatic saving process. Therefore it is recommended to "zero out" the board every now and then. This recalls the factory settings (based on the actual firmware) and makes the board work as intended by the manufacturer. For checking problems it is always helpful to start from there.

A "factory reset" would be the next step, if a problem can not be solved. Many times a factory reset "repairs" things (makes things work as intended). You just have to be aware that ALL your settings get lost by a factory reset...

But first let us know what the result of the routing test is.

Ok. Channel 19 does not mute when assigned to the mains. Only to Aux 1. It does not even require a power cycle to occur. All I have to do is hit the recall button and I'm back with no signal into Aux 1.
I get it working by pressing the mute button on channel 19 to 'ON' then 'OFF'. Then I save the scene. I'll have the meters assigned to the Aux bus and when I press recall immediately the level at Aux 1 goes to nothing(No LEDS lit). I have channel 19 also feeding aux 3 (oops sorry my original post said only aux 1) and it does not cut out the send to Aux 3. To me this sounds like a firmware problem.

It is not a firmware problem. I have seen none of my boards doing this.

Well, now you should try the "zero out" procedure. Load scene #1, wait a few moments (let automatic saving happen two times) and turn off the board. Then turn the board on and check, if something has changed.

If nothing has changed, the only thing left to do is a "factory reset". For that you need to save the scenes and settings you want to keep, because everything in the board's settings will be erased and gone forever. The procedure is explained in the manual, in the knowledge base and there are videos about it. Check your account at PreSonus for helpful information.

Be aware of firmware changes. With the legacy boards it makes sense to get the latest and greatest.

First of all I want to say thank you for your help wahlerstudios. Please do not take my following statements the wrong way, I am just trying to understand what the heck is going on.
You say not a firmware problem, you sound pretty sure. Did you ever have channel 19 assigned only into Aux 1 and 3 on a 24.4.2 classic board? Isn't all the muting, aux send levels,fat channel settings, and routing etc... done in the digital domain? So I have a setting that doesn't work but when I give it a nudge(mute then unmute) all is well? So I have a transistor inside some DSP I.C. that is failing only at start up or recall but when I kick it(mute then unmute) it works? I'm bewildered.
I will next try the zero out as you suggest.
Thanks again

I don't know if we ever will understand a computer... Your SL is a computer inside AND it has parts that can easily get damaged (all the electronical stuff under the hood). I am sure that it is no firmware problem because I never (!) had problems like you describe. Whatever I write into a scene I can always recall it. This is the same with the old and the new SL boards.

But the settings you work with might have become "corrupted" during the time, so "first aid" is loading scene #1 (zero out board) and check settings from there. This scene brings back the board's settings and functionalities.

If this does not change anything, the next step and last step before hospital is a "factory reset", which will install everything (!) new on your board. After this total reset there will be nothing left from settings you have made. Your board will be "new" inside, so if you still have your problem then, the board obviously needs a repair.

A "factory reset" has helped in many cases, so hopefully it will also solve your problem.

loading scene 0(zero out board) had/has no effect.