Thanks for the report. Bit odd that they're not working for you.
The tags work like this:
1. Start typing a tag in the Tags box on the story submission/edit page. Note that (annoyingly) on mobile it will default to upper case first character, which won't match anything, as all tags are lower case by convention here.
2. The drop down lists matches.Scroll to find the one you want and click it.
3. If the one you want isn't there, double check your spelling. If it's still not there, select the "Create 'your tag'" entry at the bottom of the list. What sometimes happens for tags with popular words (like 'pussy') is that the select list isn't long enough to show them all. In that case, just use the "Create" option at the bottom and, if it matches one that's already in use but isn't shown, it'll assign it to your story.
4. Repeat, up to a maximum of 10 tags.
At the moment the tags are still a bit of a mess. There are ones with hashtags at the start (ugh), ones with random punctuation like apostrophes or quotes or full stops at the start or end, misspellings, etc. Pretty much everything.
I've been going through the last few days and tidying them up as I spot them but it's slow and laborious with the tools we have available at the moment. Hopefully we'll get some more powerful tag admin tools in future.
I'd also love it if the tagger would remove hash characters and full stops automatically, and treat a comma-separated list that's typed in as separate tags. Maybe one day.
In the meantime, it would help massively if everyone avoided tags with odd punctuation characters in them, as it helps us to weed them out by hand.
Thank you.