In November, we released version 4.05.01 of the mobile apps (iOS, Android) which included changes to standardize the phone number format to conform to the E.164 format. These changes included pre-populating the country prefix on the dialer.
In result, when dialing short codes (including emergency numbers 911 and 988) you must manually delete the country prefix before dialing the short code. We realize this can be an inconvenience, so we are working on an update that will automatically remove the country prefix when dialing short codes. We plan to release this update in the next 2 weeks.