When in technology tree (makes main UI disappear), game still can be 'paused' (I mean the grid view, shift-space by default). It's then possible to enter the menu (Escape), and save the game; then during the next load the UI will be still hidden.
The issue seems then to be tied to the save.
What works correctly: just shit-space doesn't make the UI disappear, so it's visible next load if saved. Just technology tree doesn't allow to save (Escape quits technology tree, at least by default).
[Oxyd] [0.17.0] Tech screen + pause + save can make UI disappear semipermanently
Re: [Oxyd] [0.17.0] Tech screen + pause + save can make UI disappear semipermanently
Thanks for the report. This is fixed in 0.17.2.
If you want to get ahold of me I'm almost always on Discord.