Update - To expand on this issue, the change only appears to cause issues when placing a call on hold via the Web Phone, and then retrieving the call. No other web phone functionality appears to be impacted.
Feb 14, 10:36 EST
Identified - Google recently released Chrome version 72, which introduced an issue with the portal Web Phone Client. We expect to have this resolved shortly as our developers are currently working on a fix.
Feb 14, 10:33 EST