Category and hashtag searching issue

Hello

i have trouble with tag searching function on my profile and i also think i have broken a category due to special character.

Let's go for hashtags first:
schmaker.eu/search?tag=Unihert… returns nothing
Category also does not work (special character issue?):
schmaker.eu/profile/schmaker?c…

This public post has #Unihertz and is in "IT & technologie" though, so it should be discoverable with former links
schmaker.eu/display/c83e3896-1…

Anyone experiencing similar behavior?