This is a generic bug for improving various code chunks in PV wrt floating point handling (e.g. comparison).
One specific issue in practice was #1149, but recently another problem occurred with hantek-4032l voltage thresholds (same reason as #1149, a different fix will be needed).
The compiler option -Wfloat-equal can be used to find all (or at least most?) issues related to direct floating point comparison via "==". Other FP-related issues in addition to those might exist in the code-base, though.