Row height shortening to obscure text between document close/open

Mojave 10.14.6, LO

In the attached document, when I close and open it, the Row Height of some rows shortens to obscure the text in columns L - AP, rather than staying at the appropriate height at which it was set.

I then reset the heights to be the correct height again using Optimal Height each time I open and close the document.

Normally this wouldn’t be such a big issue, but due to the nature of how this document is used (it is closed an opened fairly often) it’s rather inconvenient to have to set rows to Optimal Height every time it happens.
Plus I’m just wondering why it’s happening at all.

It does use Conditional Formatting based on another (sensitive, therefore I haven’t included here unless I need to) document, however I fail to see why this should be an issue.

C:\fakepath\Rhythmic Conventions List (R.R.D.T.).ods

Amended version with unmerged cells (see comments below:

C:\fakepath\Rhythmic Conventions List (R.R.D.T.).ods

Though, I can’t see a problem on my LibreOffice installation, I’d strongly recommend to reconsider the excessive use of merging cells. I can’t see any reason why to merge columns L through AP of a row, instead of setting column’s L width to 31*1.26" = ~ 39"

There is indeed no reason, it’s simply poor formatting copied from another sheet whilst I was playing around with a few things.
I’ll unmerge the cells and change the width to see whether or not it helps.

After splitting the cells and changing the column width containing the red cells 99.2cm (which is a good width for my purposes), not only do the row heights still shorten to obsure the text, now the width of the column containing the red cells also shortens to 33.6cm upon closing and reopening!

Have included the document in the post; could you let me know whether or not you experience this problem on your LO?

I do get 33.6 cm as well