ITH-20R indoor monitor only shows 2 of the 3 sensors

I have the ITH-20R temp/humidity sensors (3) with the IBS-M1 WIFI gateway and the ITH-20R indoor monitor. The indoor monitor only shows 2 of the 3 sensors on the screen. When I select channel 8 it rolls through all three channels but shows channel 1 with no data. Channels 2 and 3 display data.

In the Inkbird app all three channels show data. Is this a defective monitor? Any information would be helpful.

Hello, is this forum monitored by Inkbitd?

Please reconnect the ITH-20R-I receiver and ITH-20R-O transmitters.
Please press the TX button of the ITH-20R-O transmitters (needs to open the back of it), and CH/R of the receiver for about 5 seconds.
Uninstall the batteries of them.
Please reinstall the batteries of the ITH-20R-I receiver first, then reinstall the batteries of the ITH-20R-O transmitters within 2 minutes. Please put the ITH-20R-O transmitters close to the ITH-20R-I receiver.
If they synchronize successfully, the ITH-20R-O transmitters will flash a red light once.
Can it work?