SDL Trados MultiTerm does not work

Hello,  since several months my Termbase often fails to work properly. Errors when adding a new term, frequent blockages on the fly, existing terms that just do not show up in the 

Results Window, failure by adding new term on the fly are the most common errors. At the moment, for instance, it just can't help my translation task when I need it so much!

Anyone can help me please and explain why this happens and how can I solve this problem. It is causing real trouble and I do not want to keep an useless termbase! 

I have got Trados 2019 but Multiterm is still 2014...

Best Regards, Maria