It seems your experiences with DP832 match quite closely with my experiences with DP832 and this Symmetricom unit.
Maybe the DP832 current limiting kicks in quicker than the other supplies? In those scope captures there were spikes up to 8A when the converter tries to start.
I believe I have seen it mentioned somewhere that the correct voltage for the Trimble version would be about 6V. So could be similar for this Symmetricom version. So maybe 5V is just too much below the intended supply voltage for these.
Oh, believe me, I tried starting my board with 6V and limiting the amps and raising them only to find the DP832 clamping down at ~3V. Even dialling in 12V supply didn't help, the DP832 only supplied ~3V and the TI boost module would be ringing. I measured the VIN at the board with a DMM and sure enough it was clamped low no matter what you set the DP832 at.
That was with the TI module. Remove it and power with seperate 5V and 12V from the DP832 and it works great. But I switched the TI module for a cheap XL6009 module and found the same clamping the voltage low and oscillating when powering with 5-6V and 3.2A on the DP832.
Using my HP 6632B and my cheap ass Tenma PSU's I observed the same 3V clamping behaviour if powered with less than 1.6A CC, even when winding the current limit up to 5A.
I found starting with >=1.7A @ 5V it works just fine. Just not with any V or A on the DP832