Switch status does not change in ST app

[git-isu]

Using the following:
Sonoff Basic
Tasmota FW v6.4.1(sonoff)
iOS 12
v3 ST hub

ST legacy app - button changes switch state but always appears as "ON"
ST modern app - Error: Couldn't connect to sonoff_sw3. Try again later.

This issue was not reproducible on a v1 ST hub