Recently we've started seeing a "Unable to Submit - Unable to complete operation" error message when trying to submit our GPS data using Collector (v19.1.0, iOS v12.4.1). It's intermittent and the data will go through if we attempt to submit it again (however, sometimes it takes multiple attempts).

Anyone know what's going on? I'm not aware of any changes on our end that would correspond to this new error message. We've enjoyed collecting GPS data with Collector for years without experiencing this.
Any help is greatly appreciated.