create a new brain & a couple of thoughts. Change to Tags/Keywords (German: Stichworte) and hit the green plus sign. Enter "1", close the upcoming dialog. Do the same with "2". Result: Neither tags show their text ("1", resp. "2") in the Tags-overview. As soon as one enters a tag with alpha-chars, they are shown.
This behavior i under 220.127.116.11 under MacOS and java 1.5.0_22, maybe 1.6.0_7 (about dialog and java -version show different values and i'm new to mac so i don't know which it takes atm).
-- 18.104.22.168 (22.214.171.124) on Mac OS X 10.12.6
Old enough to remember Natrificial times...