The transaction log for database 'database_name' is full due to 'XTP_CHECKPOINT'

I have a question about XTP_CHECKPOint.

I'm using SQL Server 2014. I have a database that is in SIMPLE recovery model mode. It is also being replicated.

There are no open transactions. I've run DBCC OPENTRAN and it returns, "No active open transactions."

But I keep getting this message whenever I try to create or drop a table or delete data:

"The transaction log for database 'database_name' is full due to 'XTP_CHECKPOINT'" (I've replaced my actual database name with the word database_name.)

Does anyone know why this might be happening, and, more importantly, how I make it stop?

And yes, the database really is in SIMPLE recovery model mode...i.e. the transaction log should truncate automatically.

Any ideas?

Incidentally, another database that I have in full recovery mode did the same thing, started returning the same error:

The transaction log for database 'database_name' is full due to 'XTP_CHECKPOINT'

I tried to change the log growth settings to unlimited growth, but it wouldn't let me, returning the same error.