Since PIC to PC is working then I have three thoughts on this.

1. one or both modules are not working. You may try here to change the modules between them.

2. Settings are not the defaults

3. The feeds to the modules are reversed (tx to rx etc).

The modules need true mode and not the inverse you just tested with the PC. But I suppose you will change your code for this test.

Wish you luck, cannot see anything else now...

Ioannis