Heart rate is typically required to be listed in race results on ZwiftPower, and thus heart rate signal is important. When a channel drops to a HRM, for example an ANT+ dongle becomes dislodged, the HR signal is lost. However, if the channel is restored, then the HRM remains unpaired, and must be re-paired. The pairing screen for HR and power causes the avatar to come to a rapid stop, and re-pairing is typically impractical.
A better approach would be, upon restoration of a lost channel, to check for devices which were paired at the time the channel was broken, and attempt to re-pair with those devices. For example, if an ANT+ dongle is disconnected, then re-connected, Zwift would attempt to re-pair with any HRMs, power sources, or trainers which were connected at the time the ANT+ connection was lost. This re-pairing may fail, but attempts should be made over some time interval, for example 10 seconds.
Of course, the avatar also should not come to a halt when the pairing screen is entered, but that is a separate feature request.