When LLD rule check fails with not supported error it is put into history cache and processed by history syncers. The item state and error is compared with configuration cache state/error and cache/database is updated only if values differ.

When LLD rule check succeeds it updates its state/error in database, but in configuration cache the old state/error remains.

While it doesn't seem correct to have the supported/notsupported rule processing split, for now it would be easier to simply update configuration cache when resetting item state/error after successfull lld check.