Though I've been consulting this forum for a while, this is my absolute first thread, so I apologize in advance if I haven't included some critical information needed to troubleshoot my issue. I've looked around here (and other online resources) for hours but I haven't seen anything that really describes my issue, so here goes:
Device: dsPIC30F4013, MPLAB X IDE v5.40, Compiler: XC 16, Programming device: PICkit3. OS: Windows 10
Functionality description: The program's main loop counts up the number of times a button is pressed (pin RFO) and prints the current count to an LCD screen (this part works fine). I need to write 3 interrupt routines which will read 3 NPN inductive sensors, each of which shall print a unique alarm message to the screen. Only after the sensors are reset (they're "seeing" metal again) AND a Reset button programmed at pin RB1 is pushed (as an acknowledge button), should the program return to the main loop where it can count again.
The NPN sensors I'm using work at 12VDC, and I'm using 3 PC817 optocouplers to isolate this high voltage from the 5VDC I'm supplying to the dsPIC30F4013 (and the signals the optocouplers send). I have checked that these devices work properly and that they're only sending a signal when they're supposed to.
I programmed the 1st interrupt at pin INT0/RA11 and this worked as expected. I then copied most of this code (modifying the appropriate registers) and am now also using INT1/RD8  as input for the 2nd interrupt routine. The program compiles with no errors, however, when I test this on my PCB, only one of the interrupts works. When I comment INT0, INT1 works as expected, and vice versa. They cannot work simultaneously. To clarify, I don't mean that I can't use nested interrupts (this isn't what I'm trying to do), but that when I energize the dsPIC, only 1 interrupt works at all. Note that the interrupt that works is always the same one (whichever was the most recent one to NOT be commented before I uncommented both interrupts).
For the sake of brevity, I've included my code in a .txt file for your consideration.
Thank you very much for any help you might be able to provide.