Status vs. out of sync?

There are two cases where I’m finding the “Out of Sync” status confusing.

a. When can a Master folder be out of sync? It seems to me that by definition a master folder is always in sync.

b. A folder being considered out of sync when files in .stignore are missing. Isn’t that the point of .stignore, that certain files lack of sync is “as expected?”

[Sadly as a new user that screen shot will have to be placed in a following post. Apologies]

If there is a better place to make these observations than this old thread, apologies and please advise.

Hamish.