My usual technique is inflate with a tube, remove tube leaving one wall on the rim etc etc
I'm not getting past this first stage, I inflate with a tube, remove tube and the tyre pings off the rim as I'm inserting the tubeless valve.
Anyone got a tip for this? I've done loads of different tyres and never experienced this before. I'm trying a UST mountain king and a UST rubber queen and both are doing it.
Maybe I'm not leaving them inflated by tube for long enough? Only a few minutes.