This started only recently for me, but I've seen it in both 1.92 final + patch 1 and 1.91 final + patch 1.
Sometimes certain sprites that are displaying fine will stop being visible the next time I run the simulator.
When checking this sprites, I see this:
... and I need to select the sprite collections again.
This last time everything was working fine, then I made an edit to a script and saved, ran the simulator again, and my sprites had lost the connection to their collection (the script wasn't attached to any of the objects in question).
Not sure if I'm doing something silly here, or if this has been reported already, but I'd love to know what I can do to stop it from happening. Thanks!