I’ve tried on current master. I’ve tried without add-ons. On ubuntu.
The reviewer blinks usually when I move from side to side or to new card.
The same style create no problem if it is directly put in the style part. However, I prefer to import style, because this allow me to use the same style in all documents, and more specifically to update a single time to get the update everywhere.
As a side note, it seems you forgot to add 2.1.48 tag in git
(Seems the tag is not set on the commit where tag number is incremented, which I find even more surprising)
I usually use those tag to ensure that I look at the correct version of the code when debugging an add-on. On the one hand it is less easy to debug. On the other hand, I guess at least now I know I was not lo°oking at exactly the good commit.