Hard to say then. The only other potential which I highly doubt is that you have the Related Field and the Proxy field on the same form causing a data corruption.
Beyond that - the only thing I could imagine would be a Pipeline/Webhook/Action that is blanking it out. Are you confident that there are no webhooks in other tables or Pipeline that is using the 'Request' step instead of a Quickbase step that might be targeting that field? Its possible that if you're doing a webhook payload that targets that particular field, it wouldn't show under usage since it would just be targeting the field ID in plain text so QB wouldn't register it's usage.
If all routes fail even then to find the answer - I might recommend doing a short term log of the field. Just setup an audit trail on that one field, track the new and old value along with the user that changed it and when. If you see the User A changes it one minute and then a SVC account changes it 1 second later - it doesn't give you any answers but rules out user error for example.
We've made a few changes to our pipelines and have turned off our action items (for a short period). We will monitor and see. Thank you.
