I've done precisely what you did multiple times (A/B/A) in "strictly follow" and it reacted differently. 'A' started and 'B' acted as the bench and reserve each time. I've done this for training purposes when I wanted 'B', a higher priority trainee, to get the final <10 minutes for his 48+ training minutes after they were randomly subbed out, hurt, or fouled out in a previous game. It's never worked but I still try it.
But yeah, yours is a bug. Mine aren't. Yours reacted like "coach picks".