tried them side by side on the same stainless piece, I found a 1 inch long piece of silver braze thats very old (2016), wet fine, stood up to grinding, made a round puddle.
The new piece made a big droplet that did not spread out and made some weird shape that kinda adhered to the metal, and during melting it did not wanna wet the steel, looks like a portion of it got ripped off by the belt sander. It's not wetting right.
into the trash bin that went, fluxed both with the same old flux btw and soldered at the same time.