The UHRS report usually updates in regular intervals of approximately 30 minutes.
It may happen at times that this is not working as expected and that the report remains unupdated for a much longer period of time. There have been occasions in the past where it took almost 24 hours for it to properly update and show the correct number. However, no earnings were ever lost during such occasions. It alway appeared properly once the report updated. So there is very little to no risk of actually losing any earnings if you continue to work on UHRS when your report is stuck. However, this is yours to decide. If you want to be 100% sure not to lose anything, you can consider to stop working until the issue has been solved and the report has actually updated again.