Have a try to restart the three deco and try another phone？

Update to issue.
Restarted Decos a few times and nothing changed.
Left the app for a couple of hours went back to it when it opened with only one of the three Decos again but.... within seconds the home screen refreshed to all three
Left everything over night as I thought it had corrected itself.
Midday started the app again and it was back to one Deco--- hmmm!
Borrowed my wife's phone (S8) and setup the app (and her as a manager of the network), which started normally and showed all 3 Decos.
Back to my phone restarted app and it was back to three, so into tools and Managers which puts up error message "FAIED TO GET INFORMATION. Please try again later"
Entered the "+" on the upper right and added wife's email as manager and saved. result message "Unable to add. Try again later,"
Now I'm not totally certain but I think Managers/owners are stored in the cloud, but every time the app shows only one Deco the Wi-Fi/owner details show an incorrect owner/manager detail as indicated on my first post.
Can there be an incorrect data transfer to the app?
I have also found that doing a Forced Stop on the app temporarily rectifies the situation.
Hope this helps anyone else with this problem.

It seems your phone has a slow response to Deco APP.
Perhaps you just need wait more time, then the deco will show up.

Same problem here: only one Deco is displaying in the app :confused:. I let it search for minutes and only the one is visible (always the same one). When I check via WiFi analyzer i can see all three are broadcasting.
Ps Deco is in AP mode (hope they fix the alternate IP range soon :rolleyes:)

I will recommend you either switch to an another phone or restart the three deco or wait for a while because it seems that you've a slow response rate to the deco app.

Are the deco running the latest firmware and all connected to the same router or switch directly?

All Deco units are on latest firmware. And connected to the same router (although some are linked via switch). The only Deco I can see is connected via a switch. One is connected directly to the router and one is connected to another switch.

Deco (not viewable)
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Router --- Switch ---- Deco (viewable)
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Switch Deco (not viewable)

Are they working on AP mode? Try turn off the the two Decos which are connected to the switches, only power on the one connected to the router directly, and check if you can see the Deco on your APP.

jdotmm wrote

All Deco units are on latest firmware. And connected to the same router (although some are linked via switch). The only Deco I can see is connected via a switch. One is connected directly to the router and one is connected to another switch.

Deco (not viewable)
/
/
Router --- Switch ---- Deco (viewable)
\
\
Switch Deco (not viewable)