Sounds like you have artist? 2 way, convert to wav before importing. Itunes can do that, or there are other freebies that will.
Option 2, purchase the mp3 add on for artist in the presonus shop, and then you will be able to import, and mixdown, to mp3
Lenovo ThinkServer TS140 Win 10 64bit, 8GB RAM, Intel Xeon
Lenovo Thinkpad E520, Windows 7 64bit, 8 GB RAM, Intel i5 Processor
StarTech EC13942 34mm Expresscard
S1Pro V2 , Melodyne Studio 4, Nomad Factory Studio Bundle, Waves , RM16, Studio 192, DP88, Faderport, Central Station Plus, Yamaha HS50 Monitors, Sceptre 6-8 Monitors, Temblor 10.
If you want work with mp3 files in Studio One then I recommend to read this thread: https://forums.presonus.com/viewtopic.php?f=151&t=23770.
What that thread is talking about is the fact that mp3 files have a little space at the front of them.
That's true of whatever DAW you use.
When I used to collaborate with mp3's you would need to clip off the space and move the clip to the start.
That way it will be in time with the song. It seems fine for a quite a few bars but later in the song the timing problem will be noticeable.
You would probably need to do that with a converted wav, easy to check, just zoom way in at the start and look for space.
I'm not saying the .mp3 files are sample accurate with their respective .wav files. But they aren't totally out of sync as some of you demonstrate.
Images show three tracks:
First track is original wav. Second track is .wav mixdown then converted into .mp3 by foobar2000 and that .mp3 is imported back into Studio One. Third track is .mp3 mixdown then imported back into Studio One.
First image shows start of the song. As you can see, first two track are perfectly aligned (with respect to 1ms timeline resolution). Third track is 25 ms delayed.
Second image shows end of the song. First two tracks are still aligned and third one is still 25 ms delayed.
Note: There is nothing wrong with working with .mp3 files. At least Cubase users talk to me this way (in truth, they are much more specific:"Buy to yourself respectable DAW which works"), and there is many such users around me (in fact everybody, becase I'm only one with different DAW). In other words, everybody around me works with .mp3 files just fine.
Note2: Of course nobody will send mp3 files to mixing engineer, but they are good enough for composing phase (but not in Studio One).