Create index on hyperscale SQL database inexplicably stops on large table (using WITH... ONLINE and RESUMABLE))

We're trying to create an index on a very large table in our PollenSenseLive db. The first time we tried, it failed after a few days, and we deduced from the start time that the server had rebooted. Unfortunately, we were outside of the short time to resume.

The second time, after over a week and about 60% completion, it inexplicably stopped. select * from sys.index_resumable_operations returns nothing, and the server doesn't appear to have restarted either.

Here is our statement:
CREATE NONCLUSTERED INDEX [IX_TagCategory_FrameId_CategoryCode_Probability] ON [dbo].[TagCategory] ([FrameId],[CategoryCode], [Probability]) WITH(ONLINE=ON, RESUMABLE = ON, data_compression = page)