Pretty much the same issue if in the WOL agent list if you add blank line feeds or blank carriage returns.
That was fixed for version 7.7.4, released 2020-03-07
https://www.ubbcentral.com/changelog.php#774[FIXED] CP: Fixed the long-standing bug of the Whos Online list being empty when an additional new line (blank line) was added to the end of the Robots/Crawlers (Search Engines) list.
It was also fixed in a number of other locations.
