iMac crashing after memory upgrade, .AssetData issue

As mentioned,Mac’s are very RAM picky.

In addition to having a bad or a loose module, the RAM could be incompatible.

I would proceed with your 2 module testing and then if that doesn’t help. I would reinstall the factory RAM modules and test.

Then I would request a refund from the seller. Next I would purchase a couple of 16GB modules from OWC and add those to the factory RAM modules.

https://eshop.macsales.com/item/OWC/2666DDR4S32P/

i would return to the original RAM that came with your Mac -- make sure they are in the correct slots (slot position matter)

if those work -- swap in the two aftermarket and test (remove the good RAM)

if neither work now -- i would suspect bad install (possible conflict) or bad hardware

bad install: Erase and install -- to an external SSD -- add the suspect only -- reproduce the problem

bad hardware -- return Mac to factory original hardware -- remove all non-Apple mice, keyboards, hubs, cables, ect...

ps: strong electronic interference -- like a microwave close by -- can also cause issues

macs are pretty picky with memory modules, so modules it would view as periodic defect would cause exactly what you describe

I would, and I would be sure the remove the ones in pairs in terms of dual channel pairs