Hi
I'm having the same issue - did you ever get an answer that helped from TP?

Do you guys login to the app with owner account?
And you do connect to the corresponding Deco Network?

I had to set up two accounts during my deco time, one for tp cloud, then another one for this forum. The login I used is specific to the forum.
However, I have given up on Deco, too many issues to sort out - ip6 I did manage by changing dhcp mode and playing with bridging.
However, the connection to the ISP router was not reliable and the music streaming was not consistent, so the Deco is packed for return to retailer - life is too short to spend weeks setting up a wifi router imho..
Pity really, looked smart and had good wifi for reasonable price.