Endless loop in VBA dotm Word 2016 with search text

In Word 2013 we have no problems but in 2016 we have randomly an endless loop. We do an Includetext and we look in the field for certain characters. Due to whatever reason we have an endless loop, but not for all situations. Sometimes it processes ok.
We already repaired the XML of the included  building block. Then problem solved, but today endless loop again with the same input.