Recording through mixer/recorder, no sound on playback

I’m using a hp Pavilion with Windows 10, just downloaded audacity 2.1.1 the other day

Using an iMultiMix8 Alesis mixer and a good quality mic.

While I’m able to successfully record and playback using the internal mic on the laptop, it’s not so straightforward when going through the mixer.
So the mic is connected to the mixer, can hear everything perfectly. Can’t see the db levels changing, but when I hit record they move as expected. Then when I hit play it no longer plays back.

I’ve tried every combination of playback and recording device out of desperation. Hair is being torn out. The worst thing is that we had it working yesterday and then it abruptly stopped playing back what we were recording, as far as we can see we didn’t make any changes in that space of time.

Any help is much appreciated

Audacity does not officially support Windows 10 yet, and it seems your mixer does not support Windows 10. So unpredictable behaviour is possible.

Do you have the expected tall blue waves after you record? If so, choose the playback device you want to use in Audacity’s Device Toolbar. Occasionally Audacity playback can just stop working for no apparent reason despite playback can be seen in Meter Toolbar (this isn’t specific to Windows 10). If that happens, try shutting down the computer (Win + X menu > Shut Down, not other methods).

Also check the mixer (read its manual). If you don’t see the meters flashing when you record, that may tell you something.