So youre source is high Z and when your vout is not in regulation, the TP61202 error amp is railed high so it sucks in as much current as it can….the volt drop from this high currnt draw across the source from that then takes down your vin, and the thing keeps resetting…..etc etc ad liberatum.
One way round this is to change to an input current regulated boost converter. Or an input voltage clamped boost converter…so it stops working when vin gets so low that its just about to reset the chip.
Or just put up with the kind of on/off behaviour and kind of “make it work” for you.
Can you not have another TPS61202, which is loaded extremely lightly, and all it does is power the main TPS61202?........
What size is the input cap at the output of the solar panels?
What is the maximum load on the boost converter?
A schem would help if you can.....though i know if you are in a big co, that even though the circuit is "pretty standard and routine", your companys (unofficial) forum watchers will be upon you if you post the cct. Reporting you to the gaffer...(even though you posting this simple scheme would do no harm to the co whatsoever...so please post if you can.)