ODT/ODT and ODT/ODS self-incompatibility issue?

I’m having an odd LibreOffice seeming self-incompatibility, which manifests in two main ways.
I first installed LibreOffice in late April, so it’s only been a couple of months. Things worked very smoothly for awhile.
Then, literally mid-edit (had 2 .odt files open like always and was cooking along (I’m not using .DOCx et al 'til I’m done with a file and convert it to that)), I suddenly could no longer select text in file A to paste into B (or the reverse), AND in file B when I right-clicked anywhere the pop-up menu appeared but was just a blank grey box with nothing showing or even ‘invisible but still selectable’.
Then, this started happening between .odt and .ods files, and THEN even just opening an .ods file at AT ALL while an .odt file was open started causing the machine to race-- or at least the fan goes wild, to a scary degree.

System:
MSI Stealth GS75 / MS-17G3 laptop
W10 Pro 22H2 x64, build 19045.5440
LibreOffice 25.2.3.2. Problem began with 24.8, but current version doesn’t seem to help no matter how many un/re-installs are performed.

A couple other specific items:
–I open all files individually via start menu/right-clicking on the proper libre icon to get the ‘recently open’ pop-up, and choosing there.
–This machine is airgapped: I’m trying to retain a useful, non-copilot-besoaked couple of W10 machines and not upgrade them to W11 (that ‘upgrade’ is quite unwise to do with any personal info on-machine, IMHO), so I will not be further updating W10 or otherwise exposing this machine online anymore. These LibreOffice install versions are DL’d on a W11 machine, copied to a backup USB drive, and then uploaded to this machine with this odt/odt and odt/ods issue. But again, things worked VERY smoothly for almost 2 months before going sideways: I hadn’t installed or uninstall anything else, changed any settings, etc. This machine is also having a LibreOffice/VLC Media player compatibility issue (calc won’t filter with VLC installed, apparently, see separate post), but that began AFTER this odt/ods one.

Turn off any additional clipboard manager.