Highlighting / selecting words

Some words I’ve never seen before are not highlighted, so I try to highlight / select them so I can add a LingQ but they can’t even be highlight. And it only happens for certain words. I can pick a different word that is unhighlighted and select it with my cursor and I can then add a LingQ, but some are weird and I can’t. I try selecting the whole word, part of the word, everything. Why are some working and some not? And it seems all the words that I can’t select for some reason are ones I don’t know and ones I can select are ones I knew, even though none of them are highlighted in blue or yellow.

We do have an issue with the occasional sticky word. It is on the list. It is relatively rare and I do not let it bother me.

It’s the linguistic equivalent of poltergeist activity.