storyline 360 can't save my project (low memory error)

Hello,

I'm working on some project. I have done 5-4 slides. Sudenly SL360 starts to work very, very, very slow (almost can't do anything in it). I can't even save my project. It's happening to me few times already after working with one file for 3-4 hours. I'm sending screenshots from two errors (I'm getting those when I try to save my project). I have 32 GB of ram, so it's not a problem. I'm working on windows 10 64bit.

My slides contain: 4 photos, 15-20 buttons, 15-20 text files, few shape objects, 10-15 layers with one audio.

edit: SL360 starts working slower gradually.
When I reopen my file, it's all good and program takes only 400MB from memory. I think taht problems start when it's reaching ~3GB of RAM.