Definitely seems like a server issue. But let me know what they say. It might still be something I can tweak in the code, once they can tell us what the issue is.
On a different issue, you might be pleased to know that I have just joined you as a MAC user :-). So I may, once I get used to it, be better able to see any specific MAC problems you come up against.
It’s taking a while to convert my full development environment for various software changes, but I’m nearly there.