Did not want to necro a thread so started a new one on the same issue: SwitchBot momentary mode, also entity missing?
As per the screenshots I have the bot added and its showing the option to use the momentary as well as its in the attributes but I get the error shown in the second screenshot when trying to use it through HA.
edit: forgot to add a screenshot of the integration page and will be using the switchbot app on the phone to control it until a fix is presented.
I have opened a ticket at Switchbot Intergration Issue · Issue #4498 · home-assistant/supervisor · GitHub to try get this resolved.
Update: I had to redo the password on both the app and in the integration to get it working, even though password was the same it only started to work when I redid it again.