DT Ints not working on 16F18426

[tumbleweed]

Not sure how I missed this the first time around, but you're manually enabling both the IOC and INT interrupts.
Don't do that. Get rid of both these lines:

    INTCON = %11000000          ' Enable GIE, PEIE, falling edge.
    PIE0 = %00010001            ' Enable IOCIE, INTE bits.

There is no handler defined for the INT interrupt, which is on the same pin as your IOC (pin RA2).
Once INT gets set there's nothing to clear it, so you never really exit the ISR... it immediately gets reinvoked when the RETFIE executes.