Importing campaigns only works with label
On version 5.13.4 and before, mapping the campaigns field upon import (in my case during a contribution import), would allow use of the campaign ID. Now on 5.17.5, it only works with the campaign label. No rows fail to import, it just skips importing the campaign. Typically it is best if it rejects the row.
This may not be a bug but it would be useful to add to release notes if it isn't already or an advisory so people don't get caught out.