I'm also having this issue.
I first noticed it some time after completing the UFO event after leaving with Mega breasts, though it could also be because I was trying different outfit sets that I had BEFORE accounting for Mega breasts. I reloaded a save that I had right after completing the UFO event and that restored everything... The 2nd time that I noticed this was before dating Bell, I first went on the date without anything appropriate covering Mega breasts then I reloaded the save to right before dating Bell and did all that I needed to do to get the plain robes by getting captured in upper New Ark, then I went back to dating Bell while wearing plain robes(also saved right before that point without first checking if everything was functional), went on that date and then I noticed it happen again, I couldn't access inv, clothes, skills or even sanctum. I even reloaded the aforementioned save and they were still disabled.