@David-TP This is also happening to me. I have the Deco X55 3 pack. I have 30 connected devices all working fine but the app just shows 8 (the 8 shown are all TP Link products too). This problem started after the most recent update. If I reboot the network all 30 clients show up in the app afterwards but then disapear after a few hours. Hopefully a new update will come out to fix this. At least my stuff is still online.

  @David-TP 
I have a mixed XE75 Pro (2.6) X55 (1.26) network... Been having issues since the Dec 1.4.0 release of X55.... so I've been testing various versions.
I have Tapo plugs and many other 2.4ghz IOT devices. 

I'm currently running XE75 Pro at 1.2.12 20240821, and X55 at 1.4.5 20241021. Pretty stable but the mobile app leaves a bunch to be desired.

Anyway, I decided to give 1.4.5 20250108 from this thread a try. The upgrade went smooth and I feel that the mobile app stats per Deco X55 improved...  almost immediately however my Tapo Plugs starting going offline/online.. back and forth. I tried rebooting but ultimately the "fix" was to downgrade back to 1.4.5 20241021.

  @David-TP 

Does this solve the similar problem when there is one M-Series in a network of X-Series or is that a seperate and yet unresolved issue?

  @QuigiboReynolds I'm just going to wait for them to release a new update. At least all my stuff is staying online, I just can't see it in the app.

  @David-TP 

When you pay us to become Beta testers, perhaps we will help. In the mean time, the amount of assistance we provide you will equal the amount of assistance you provide us, which in my case is bordering on zero (noticing that in the dozen or so queries I have posted on these forums, not one has ever been answered let alone solved).

  @QuigiboReynolds 

I decided to test this build again but went slower node by node. The last one that had my Tapo plugs upgraded this morning. They shifted nodes with no issues. Upon boot some came back to the last upgraded one seamlessly and everything is working fine now. So far my 2.4ghz IoT is working pretty good and all 6x of my Tapo plugs are working fine.