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Takes a tight system to do real time fx with low latency.

Good to put your specs in your signature, click below in my signature.

Some pictures of what you got going on would be good.

An effect in the insert section should be heard in your monitoring.

You might not be able to hear it if you also hear the dry signal from the mixer.

You have to send the guitar into S1 and not to the main outs. I think that's what is happening, you're hearing live monitoring but you need to monitor through S1.

It's recording midi? or audio? Meters bouncing on the track? More info and pics needed.

This may apply to your gear or not, but it's what I do with every guitar fx processor (Guitar Rig 6, Axiom, Scuffam, etc.).

Run mono to a Studio One mono input channel. I'm assuming you have no outboard effects and running mono from the guitar. On the S1 track you've selected to record on, select the record ready and monitor button. On that track, create a stereo bus send (not FX send). Name the bus "Ampire-Ac El" (for ref). Place the Ampire plugin on that bus' Insert (not send). You should then be able to play, or reherse your guitar and hear the Ampire effect. Also, you'll see the track meters displaying not the Ampire, but the dry guitar track. It's OK, you're creating a dry mono track along with the Ampire bussed track in stereo.
Later you can opt to leave it that way, which is beneficial if you want to edit the mono guitar track. Or, you can print the Bus FX and dry track to a new combined stereo track.

Remember, for minimum latency, reduce your buffer size on your interface/mixer. The idea here is to hear what you record in real time with a minimum delay.

I don't use Ampire, but it would follow the same path. That way, what you hear is what you get.