Hi,
Even I could not replicate not starting, I've found that if I set too much criteria into collection that needs Dynamic Calculation (Auto Playlists) MMW is progressively slower on start and use. I manage to make such criteria that needed 30 Minutes to show tracks in selected node for the collection. Meantime MMW UI appeared frozen and all CPU Cores were on 100% Usage.

Eventually I ended up in lowering criteria making Search query more reliable and managed to lover response time from 30min down to 160 Seconds to show tree node. Note that I have 120k library. To test your Theory and give us much better debug info I'm suggesting that you should test your collection setting on Advanced search which will be much safer and after you find one that freezes MMW open support ticket where we can go into more details along with keeping your privacy safe.

Hopefully this will be self-explaining
I'm pretty sure this is how the situation was started.

Thank you very much for following this up and making MMW the best

If you remember what exactly you set we will fix that as looped playlist should not crash MMW.

Yes.
The problem occured when i set a autoplaylist as criteria for a collection, and that autoplaylist was set to search among songs in the same collection.

Have you managed to determine what triggered things in first place so that we can fix it?

Used SQLiteStudio to edit the collection criteria. And got it starting again.

Hi
I didnt think properly and ended up giving a criteria to a collection that ended up in a circular reference i guess.
Can I change a collection criteria outside MMW or can I change a autoplaylist from outside MMW?
What happened is that i put a autoplaylist as criteria for a collection, but the autoplaylist has a criteria that only look for files in that same collection.
As a result MMW crashed and will not start