Weird audio phasing issue

Hey guys, I realise that this is not a question directly related to Logic Pro, however as Logic is something I use every day and has been affected by this, I would greatly appreciate any help that anyone can give me.

Yesterday, a strange issue occurred on my Mac Mini 2018 model.  I was converting a video file from .mov to .mp4 in VLC when a message can up asking (I can’t remember word for word what it said) about if I wanted it to fix/repair some audio issues.  I clicked yes, however since that point it’s almost like a strange filter has been applied over my whole computer audio output affecting the stereo image in a weird way.  It affects everything - Logic Pro, Apple Music, web audio etc.  It doesn’t appear to be to do with my actual audio interface though. 

I’ve tried adjusting all the parameters I can think of in the audio/midi settings and on my audio interface too but it hasn’t fixed the issue.  I am wondering if VLC installed a random extra plugin or file that has adjusted  things...

The other strange artefact I noticed is that when I went into system preferences and accessibility and chose to output all audio as mono, instead of making the output mono, it outputs as some incorrect odd form of stereo.

I don’t know if any of this makes any sense to anyone, but any help would be massively appreciated. 

Thanks

Sam