About ten years ago, by the side of a cycle path in Colchester, passers by were surprised to see a red-faced man scream “J***s T***y Ch***t! Right! That’s it!” as both the front AND the rear wheel started to deflate. For several days, our man had been trying to trace errant punctures just like the OP described, with no success.
Our man was so irate that he picked up the gently hissing rear wheel and threw it hard into a hedge. That rear wheel happened to be fitted with a Hope hub, which duly spat out the cassette and freehub upon landing, sending pawls and springs into the shrubbery never to be seen again.
The man swore some more, cried a little, phoned his girlfriend and begged her to come and collect him in exchange for a meal out. He sat on the green verge, trying hard not to look like the beaten, broken man that he was.
Dear readers, that man was me.
Since then, I’ve used slime tubes and/or tubeless and I’ve not looked back.