When applying start and stop times or a specific number of minutes to the Profile Indicator, Investor/RT is using the begin and end times of the bars in the chart to determine when to begin and end the Profile Indicator. On a Time based chart this is easy since each bar tends to start and stop at an even minute interval.
However, when adding a Profile Indicator to a non-time based chart (Volume, Tick, Range or Change bar charts), each bar does not have an even begin and end time and these times are not known until after a bar closes and a new one opens.
Example One
A user with a 10,000 Volume chart might want to profile the Initial Balance period between 9:30 and 10:30 New York Time. To do this, he adds a Profile Indicator with these start and stop times. At 10:29 right before the end of the Initial Balance period, a new 10,000 volume bar starts and it takes 5 Minutes for 10,000 contracts to trade. In this case, the Profile Indicator is going to end at 10:34, not 10:30.
Example Two
A user wishes to view a chart of all trading activity for a 24 hour session but split the Profile Indicator so that there is a separate Profile for Overnight and Regular Trading Hour Sessions. The chart's periodicity is a 1.25 point Range chart. At 9:29 right before the RTH Session opens, the market trades sideways inside of the 1.25 point range for 35 Minutes. The new Profile does not start until 10:05.
In each of these examples, the Profile Indicator would have ended cleanly at the expected time if there was a bar ending at that time (which can be had in a time based chart). When using the Profile Indicator it's important to know that it relies on clean start and ending times of a bar. If you absolutely need to use a Profile Indicator on a non-time based chart, you should consider keeping a duplicate of that chart handy and set it to a time based periodicity for reference.