Problem learning names with possessive apostrophes in them

This has now happened twice, once for the name Lutwin’s and now for Bytheway’s, these being the names of shops in something I’m writing.

I have taught Scrivener the spelling, but it still underlines it as a mistake.

I’ve checked the ‘personal word list’ and they are in there, but for some reason this isn’t ‘taking’ and the names are still being flagged as spelling mistakes.

I use ‘smart quotes’ so it looks pretty, so maybe that is part of the problem?

Anyone else have this?

[WIndows 10, Scrivener 64 bit]