I was buying my seeds from gray beard seeds, and I’ve never had any trouble with any other seeds popping open. I did have one of them germinate upside down and I have no clue how that happened.
I’ve had them germ upside down. It’s just how they’re oriented in soil some times.
The other method I suggest is placing in moist paper towels in a ziplock bag in about 80° F environment and you’ll get good germination rates as long as your patient. Most should pop in 24-48 hours. You’ll get some stragglers out to 3-4 days.
Try this ph your water to 6.5-6.8 throw in 1.5 tsp of pyroxide to 1/2 c water let it soak in that for 12 hours the fold it in a paper towel mildly moist of that solution ,ziplock it and put it under a bowl for complete darkness in a warm place and check every 24 hours (usually only take 24 hours for me)
I have been in your shoes. Drives you nuts. I thought it was some thing I was doing. It was the seeds. My heat mat is set at 78 and shut off at 80. So right where @Covertgrower says. I always make sure to let them soak up enough to sink before going into a ziplock. Just what works for me. If they don’t sink. They get tossed