Hello,
Problem is in grid. So far first argument to column’s template function was of original type - string, boolean or number. After last update, previous developed software works unwell because type of cellValue is never boolean but number or string only. It impacts in bad way to software based on older dhtmlx version, so fix is incompatible with older version and that is not described anywhere in changelog.
Sample is there: https://snippet.dhtmlx.com/kit8x4e9
Swich version of dhtmlx between 7.3.8 Pro and 7.2.5 Pro to see difference, but change was between 7.3.6 and 7.3.8.
I guess you changed it to make filter working on boolean column, but you should rather fix filtering function instead of changing data type, then everything would work well.