UDPCi not detecting heartbeat in 1.3.74

#### Issue details
UDPCi does not connect to mavlink 8266. This worked well in 1.3.73. There is a new behavior when I restart mission planner, it automatically tries to connect by UDP to the Mavlink in client mode. It connects and updates the hud, but no parameters are downloaded. If I disconnect and try to reconnect using UDP only setting, it fails as expected. When I try to connect with UDPCi, i see the initial request go to the Mavlink bridge, mavlink data is being sent through the mavlink bridge, it just isn't being received by MP.

#### Version
1.3.74

#### Platform
[ ] All
[ ] AntennaTracker
[ ] Copter
[ ] Plane
[ x ] Rover
[ ] Sub

#### Airframe type
_What type of airframe (flying wing, glider, hex, Y6, octa etc)_
rover
#### Hardware type
_What autopilot hardware was used? (pixhawk, pixracer, PX4FMU etc)_
pixhawk
#### Logs
_Please provide a link to any relevant logs that show the issue_

Reproduce the issue in Mission Planner 1.3.74 with a Rover, Pixhawk, and Mavlink 8266 using the UDP and UDPCi connection modes described. Compare behavior with 1.3.73; done means UDPCi receives the heartbeat and downloads parameters after the Mavlink bridge sends data.

Written by the indexing model from the issue text.