You haven’t provided enough detail to determine whether or not this is a bug.

What are all the relevant fields, and what are the formulas used in those fields?

Rollup Formula - Formatted as currency with no decimals.

Name Formula

Jacob at Airtable Support helped me resolve this. There was no obvious circular reference, but the issue was apparently caused by using formulas to create primary field names in the related table that referenced the primary field name in the host table. The circular reference was caused by the rollup because it was referencing the linked records; whose names were referencing the host table. Don't worry, I'm confused too. 😕😕