This makes completely sense. Should be an easy fix. Right now I'm quite busy on other things. But I may have some time to take a look at this.

Found out that the "issue" comes from sensor.py L184. We should pick a different value from home-assistant:core/const.py.
I can't find an accurate option, so I'd create a new one called "none".

Having state for something else than unavailable, unknown or actual timestamp will cause state will be rendered incorrectly in the UI because of timestamp device class we're using.

To set none we need HA to support it.

OK, I understand (it is annoying as HA itself flags the entries suspect, but I understand it first needs to be supported by HA for timestamp types) I might raise an issue in HA for it (not sure where to raise/report it)

Having state for something else than unavailable, unknown or actual timestamp will cause state will be rendered incorrectly in the UI because of timestamp device class we're using.

Shouldn't the translation provided in sensor.en.json fix the bad rendering issue? Since we are setting the timestamp class. Haven't tested my changes yet, since I don't have a working development setup at the moment.

Shouldn't the translation provided in sensor.en.json fix the bad rendering issue?

I don't think so but feel free to test it.

Unfortunately I have no luck with this component. It has worked correctly once. After a Hass restart, some entities become unavailable. And now after updating to Hass 2021.08 all entities are unavailable. No way I'm going to do the "restart devices, restart Hass, reinstall component" every time I reset Hass...

@KapJI, @ArnyminerZ, i think we should replace unavailable state with unknown for now.
unavailable state brings so much confusion around . People mostly see it as "integration doesn't work, cause it can't fetch data", while in reality, we meant it as "no alarms are currently set"

Alarms that are not set should report a state of "Not Set".
Timers that are not set should report a state of "Idle".

Just my 2 cents.

This requires some changes on HA side. More details here: home-assistant/architecture#635