I just uploaded a major patch with about 30 changes. You can sit in the chair now! :)
I haven't spent an excessive time looking for the inventory bug. I just keep an eye out for it when I play test other things and I naturally use the inventory while playing, so I'm hoping to run into it and notice a reason for why it may be happening. Nevertheless, it's a pretty major bug that needs fixing, but I get your point.
There are 4 chunks in the playable area, called streaming levels in UE4. I thought that might have something to do with it, but I don't think so as I've tested saving and loading in all of them.
Concerning your mention of the video settings; They should save and load properly now. Are you referring to the overall performance and that the game needs overall optimization of the highest video settings?
As for the key binds, I plan to add customizable key binds soon, but I thought it was a low priority at this stage. You have me second guessing my assumption that there wouldn't be many players that wouldn't play just because of that. I just didn't think it was really an issue but you may be right. I should prioritize that as it's an expected feature.
Other than optimization and key binds (and the dreaded inventory bug of doom) what else would you consider a high priority? I don't expect a super detailed response or any response at all, but since you seem genuinely interested in playing and helping to improve the game, I have no other person to ask other than myself and the dark void of the internet that rarely responds.
Edit: Also I don't use anything else like github for feedback. There is a "known issues" thread, but I haven't added anything to it for quite a while and most stuff on there is fixed or outdated. Following replies and keeping my own list works for now but I will update and add the inventory bug to the issues thread if it persists.
You have been a great help and I appreciate your play testing and feedback very much. Can't really say that enough. Thank you.