cannot add terms to managed metadata per official doc

[vgyrikpceg]

I'm trying out managed metadata and have two one oddity.
Background:
I created a term set and set Submission policy to "open". I added a managed metadata field to a list connected to that set, and set "allow users to add new values" = yes. 
Oddity: 

1) I can add terms from the term set UI, but cannot add terms from the sharepoint edit item interface. when I type a new item there manually and hit enter, it highlights the new term in red and says "correct the problem." When I hit the tag button to the left of the input box, then try again, it still fails. However, when I switch to the classic interface from that screen, I'm able to successfully add terms. 
2) searching a site by terms from that set does not yield items with that term in their managed metadata column. Am I doing something wrong?  Does it just take a while for the crawler to hit updated items? 
Edit: search find the item several hours after tagging - looks like the crawler is just slow.

[#2]

It sounds like you have encountered an issue with the managed metadata field in your SharePoint list. Here are a few things you can check to try and resolve the issue:

Ensure that the user adding the term has the necessary permissions to do so. Check the term set permissions and the list permissions to make sure that the user has the required level of access.

Check that the managed metadata column in your list is correctly linked to the term set. Go to the column settings and ensure that the correct term set is selected under the "Term Set Settings" section.

Check if the term that you are trying to add already exists in the term set. If it does, then you should not add it again. Instead, select the existing term from the term picker.

Check if the term you are trying to add contains any invalid characters or special characters. If it does, remove them and try again.

Check if there are any custom scripts or third-party apps running on your SharePoint site that may be interfering with the managed metadata field. Disable them temporarily and try again.

[#3 · Accepted solution]

And it fixed itself after several days with no further changes.

Just buggy or slow, I guess.

[#4]

Nope, nothing wrong with how I was using it.

[#5]

@vgyrikpceg I just faced the same bug. I just created my term set so it didn't fix itself yet and I need to use classic view to add items which is fine for now, thanks for the tip!