SiPM soldering with T962a oven not working (Pictures attached!)
I can’t really tell from that photo, but assuming the solder paste didn’t melt and still looks “granular”, clean it off and replace it with fresh solder paste. Put it near the centre of the oven and slightly to the back, it works better if stood off with a couple bits of  scrap pcb material,

Try a hotter curve. This is a cheapie oven with not-so-great temperature control- the second run after it is hot will run hotter due to the lack of cold junction compensation. It can run acceptably well with SnPb solder using a hotter lead free curve. I suspect it will be more marginal with lead-free paste.

Consider improving the oven or budgeting for a better one (eg conveyorized),