On both Android (LingQ v. 4.9.18) and PC (Google Chrome), LingQ does not display any of my courses anymore, including content from LingQ as well as my own privately imported content. I can still access them through the “recent lessons” shortcuts on both devices, as you can see in the screenshots. I have noticed that the problem also appears for other languages I am learning with LingQ.
The problem must have arisen today since I used LingQ yesterday (and around midnight today) without noticing any issues.
Same for me. At least I can reach some of my lessons via the “recently” area so they still exist but are just not listed. In the morning (GMT+1 timezone) everything was still there.