Im thinking that maybe the seal wasnt in right or is old, and maybe you walked away … was steam coming out and pin popped up?
Sometimes steam escapes through the sides of the lid meaning its the seal.
ORrrrrr it could be something stuck in the float valve… pin or silacone to prevent a proper seal.
Sometimes with stuff like apple sauce, pasta, oat meal, split pea soup… it can spit stuff out of the holes and get crusty .
I would take the silacone cap off the pin over the counter so the pieces dont get lost… clean the pin in hot soapy water poking a pipe cleaner in the holes … wash the lid with hot soapy water and use a pipe cleaner in the hole that the pin sets in… also pay special attention to the anti block shield.
Pop it off and clean those holes well, then reassemble and tey the water test.
3 c water… time set to 3.