I agree it is very frustrating that you are losing QoBuz playlists that you created. Please confirm that your software is up to date and current. It probably is but I have to ask.
I have to ask but please also confirm that when you create your playlists, that you SAVE them. Again the answer is probably yes, but we have to confirm. I also suggest you reduce the number of songs in each playlist. It is possible QoBuz has issues working with a playlist containing 200 songs. I suggest you reduce it to 50 songs and see what happens. I hope this helps.