Isn’t the tx3 mini a S905W device if so gxl_p281_1g should be correct and you may need to create a net remote file. check CoreELEC 9.0.x Remote files
Today i tried the gxl_p212 for the tanix tx3 mini 2nd edition (without the clock in front)
remote doesnt work
will try to create a net remote file… (dont know how will try)
Remote requires manual configuration if Tanix have upgraded it.
I hope you used the gxl_p281_1g
That Tx3 Mini has a different cheap old design remote control that was used in the old MXQ S805 ND T95N boxes.
Try the T95N