We have an issue with Dell IDRAC sensors disappearing and reappearing with each discovery session.
The output of a manual Discovery session that causes these deletions is posted here: https://pastebin.com/RAW1XavT
And the log shows this:
What usually happens is that the deleted sensors are then added in the next discovery routine.
Just to add more information to this post, we have a Dell blade server where the Idracs on the individual blades do not suffer from the “disappearing sensor” issue. When I compare these Idracs with the standalone servers, the Health area of the device setup section of each blade servers is populated with what looks like the full list of sensors. That does not occur with the standalone servers. Their Health section is very sparsely populated and I suspect that might be why this is happening.