Highlighting disappears when writing

[Unpreditable]

When writing longer words, bionic highlighting disappears for part of the sentence. It's weird behaviour as it's sporadic. When trying to reproduce on other sentences, everything works as expected. Can't share original sentence, as it work related.

Specifically, I have 3 sentences, 41 words total, as part of a sub-bullet point. When I type in a word that is 8 characters long, highlighting disappears for 33 of them, leaving the first 8 with highlighting. Adding one extra char brings highlighting back. The same behaviour happens when reaching 14, 18, 25, 38 chars, but on each such milestone highlighting stays on one extra word each time, e.g. when word is 18 chars, highlighting stays on 10 words.

Overall, there are 300-350 words in the document at the moment. Don't know what other info I can provide to help investigate this.