I have Mulefüt 50mm rims and chupacabra 3 in tires. I understood the rims and tires to be tubeless ready. There is rim tape in the rims already. I removed the tube and installed a Stan's valve. I remounted the tire with a compressor. The beads appear to be well seated. I put in 4 oz of sealant. I pumped the tire to about 15 psi and there is no apparent leaking. The tire appears to hold the pressure, at least for the short term. But it looses pressure over the course of a few hours. The tire never goes flat, but drops to about 5 psi. It has held there for a few days. It happens every time I pump it back up.

Any thoughts on why the tire is not holding pressure?