I downloaded and tried it on a Ayn Odin 2 and a Retroid Pocket 3+ on Joiplay v1.20.410 and RPGM plugin v1.20.53 and it works with no problems.
Unfortunately Joiplay is still in development and its behavior may change depending on the device.
The only suggestions I can give is to check the version of Joiplay and RPGM plugin and try dowloading again the JGP, maybe the last dowload corrupted the file