Interesting. It looks like the mce_kbd decoder might be sending a key down event but no key up event.
Also odd that ir-keytable -t doesn't show anything, I'd expected to see KEY_... events from the driver.
Could you install the system tools addon and check with evtest instead of ir-keytable -t? Kodi and eventlircd must be stopped, as usual. Please post the evtest output of a short keypress.
It would also be interesting to have a capture of the raw IR signals, then I could try to reproduce that here. Could you run the following command
then press a key on the IR keyboard, then abort ir-ctl with control-c and upload the file "rawkey.txt" here?
so long,
Hias