Terms not found in DNG

Hello,
I have created an artifact type that I named "Term" in DNG. I have checked both these options
Artifact roles:
- Make this artifact type a preferred artifact type
- Use artifacts of this type as glossary terms
I have also created an artifact type that I named "Requirement" for requirements.
To be able to use terms in a collection as glossary, and also to reference these terms inside requirements.
But since 2 days, for newely created terms
Example of term:
Name: TERM_1
Alternative Spelling: TERM_1_A
Content: Initial Value == X etc...
whenever I write TERM_1 or TERM_1_A inside the text of a requirement and press CTRL + SPACE, it does not find it.
I still can find older terms that I created.
What could be the possible causes and solutions?
Many thanks.
Best Regards,
AG