Timer Capture SCS induced Problem with RAPID Captures

I was trying to use TimerA Capture for tracking how much time was spent in various routines so as to ensure a REAL_TIME system would be responsive.

 When there was at least a short interval between Captures, the use of the SCS synchronize feature worked as advertised. BUT when there was all but no delay between Captures, the TACCRx Register was set to the maximum of the possible TAR setting, definitely not the current TAR value. And of course not yielding reasonable TACCRx values. 

Removing the SCS bit corrected the very rapid capture problem.

Without SCS, what is the reasonableness of repeated captures that would otherwise work correctly when SCS was specified?