I bought one of these boards on amazon to help with debugging:

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https://www.amazon.ca/gp/product/B075N82CDL/


The PIC hangs after the first timer interrupt is triggered. The FT232 is connected to VSS and TX/RX which is wired to and RX/TX on a 2nd PIC (4K7 pull-ups).

If I unplug the USB cable and reset the circuit, the PIC starts up and loops as expected.

Is there something we should be aware of when using these?