

Those are moving goalposts. The LibreOffice devs do their best, but they’ll always be a step behind. The correct solution is to get people to move away from closed yet ever-changing standards made by monoliths who wish to retain a monopoly.
Note that I’m not saying that’s easy or even possible. Only that it’s correct.
How documents are stored by MS Office has changed constantly over the last 40 years, as have the feature sets of the different applications, for which a new variant format if not a new format outright might be created each time. The file extension is a guide but not a complete indicator of what’s going on inside.
Microsoft have the advantage of knowing the exact structure of all the previous formats so they can auto-detect and load a document transparently without the user having any idea there might have been a difference.
Because the formats are proprietary, and follow no published standard (or not fully published), third parties like LibreOffice have to literally reverse engineer every single one of those formats and variants every time a new one pops up. It’s a game of whack-a-mole. Moving goalposts like I said.
And it’s often the case that reverse-engineering a format covers only, say, 99% of cases; those used in most of the documents that a would-be reverse engineer has seen. And then someone tries to use LibreOffice to open a document with a feature from the other 1% and it looks incompetent.
There’s also that it would be illegal to decompile a copy of MS Office to figure out exactly how it does it, so they have to work from the documents that MS Office generates and take their best guess. If Microsoft got even a whiff of the idea that someone working on LibreOffice had decompiled it, the whole project would be sued into oblivion.