Hi @Patrick Lachance,
Thank you for posting in this community.
I checked the delta query document, and it does support delta query of site.
At the same time, there is no recent update record for this site:delta (the last update was in April). My colleague also tested it, but everything is normal.
Therefore, I suggest you ask your other colleagues with authority whether they have encountered the same problem. If the problem still exists, I suggest you open a ticket to ask.
Please accept my sincerely apologize for any in convenience this may cause. Thank you for your kind understanding.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.