When creating Visitor Groups that use a Time of Day critira the From and To times are not saving correctly.
There is a known bug in Episerver where the times stored for the Time of Day From and To for Visitors Groups are not converted correctly causing them to be saved wrong. This bug was fixed in Episerver UI 11.1.0 which requires Episerver CMS core 11.8. If your experiencing this bug you will need to upgrade to Episerver 11.8 or newer.
If you are not experiencing this bug and instead are seeing that you visitor groups are not running at the correct time, please see the KB https://support.episerver.com/hc/en-us/articles/360004635772-Episerver-Visitor-Groups-not-running-at-specified-times