Multiterm does not find all terms in longer segments, why?

I use SDL Studio 2014 SP2  11.2.4409.10  on Windows 8.1.  I have a small English-German termbase with 127 entries (186 EN and 216 DE terms). I have a segment that is 370 character long.  Terms near to the end of the segment are not recognized by Term Recognition and not highlighted with red color.  The terms can be found by Termbase Search. Also the segment is split into two parts then the terms will become highlighted.  The number of terms before the unrecognized term is 11.  There are no repetitive terms. The terms are lowercased, not attached to any punctuation or formatting, they are simple English words like "isolate".  Match rate, search depth, repetition settings has been tried, without change.  What can be the problem?
Thank you in advance,
Laszlo

The first screenshot shows the segment with the non-highlighted "isolate" in the first segment which is found in Termbase search:

 

In the second screenshot  the third segment  is active and shows the term "isolate" highlighted: