That is possible and I’m definitely not the insider so don’t take my word as a guarantee but if the school just recently started accepting the scores, that means they just recently received the login instructions and need to set up their accounts. This likely means they may be new to the process and so they don’t know how exactly it works or where to look up the scores and that would be more of my guess. Meaning they’re new so they don’t know where to look....
Even if you send the score right after the program has been established and started accepting the scores, they should still look yours up even if they did not have access at the time of your test or when you sent the score to them.
Oh it means is they have a webpage where they go and see all the scores that have been shared with them and that feeds into their system sometimes to make the matching easier and more automatic but a lot of times they have to match it manually...
Anyway, I would just demonstrate being proactive and professional. Don’t be a pest and don’t be aggressive but friendly, yet persistent.