Pool thermometer po2r not pairing to m2 gateway

I have followed all the instructions to set up the m2 gateway to my WiFi . So far so good .
It displays room temp and links to the app on my phone .
On the app , I selected po2r from the Gateway + Symbol. It displays temp on the po2r but it says it is offline on my app and no temp on the app or gateway.
So I removed battery, pressed button 5 secs , replaced battery , pressed once on temp controller and once on module. Nothing
Any ideas ?

If the IBS-P02R-O transmitter is placed next to the IBS-M2 for testing, then reconnect it, will it work?

No . I held the two of them as close as possible, changed batteries and tried again . The app just continued to say offline .