Terminology recognition in STUDIO 2019

Sometimes, terms are not detected in a segment, though they are in the previous or following segment ; if I select the term in the segment and try to add it to the term base, a message says that it is already in the base., which proves that the term is both in the base and the segment… Sometimes quitting and restarting STUDIO works, sometimes not. Sometimes deleting and adding again the terms works, sometimes not. This is very frustrating.