Maybe.
And, maybe, the OP has discovered some of the 'more than 120 bugs and regressions' ver 6.1.1 supposedly fixed.
I'm in the middle of another Peppermint Seven Xenial/Cosmic Cowboy Build, at the moment - just started testing it - testing it as I type, actually.

When I get done here, I'll boot up my daily driver, and check things out.
That said, I've never been a fan on Libre Office, Apache Open Office, and the like. None of them allow me to collaborate with winders users, in my work environment. Macros are always their downfall/deal breaker. It's easier to simply dual-boot '10' and use the real thing, you know?
I was shocked - even slack-jawed - when LibreOffice 6.1.1 displayed xlsm files correctly.
I looked at some contracts that I wrote in MS Word, and saved in .docx format. 6.1.1 did a pretty good job, but it's not quite there yet. The same docs saved in .doc format were spot on, however.
Anyway, back to 'monkey business'.

I'll check it out later...