UART1 was working, now it isnt

I enabled UART1 and 2 in BBB (otherwise it is stock standard, no video attached etc).

I then connected a bluetooth module to UART1, (4 pin) and it worked - I then connected a second module to UART2 (4 pin) and it worked.
Now, when I go back to accessing tty on UART1, I get nothing - no response. I have swapped devices, and UART2 always remains accessible, UART1 never responds.

Any ideas why this would just stop working?
What commands do I use to check & switch the muxing for pin?

Thanks

Some progress… I don’t know why it changed from working, to not working, but this is a comparison of my UARTS

1: uart:OMAP UART1 mmio:0x48022000 irq:89 tx:5 rx:0 RTS|CTS|DTR|DSR|CD|RI

2: uart:OMAP UART2 mmio:0x48024000 irq:90 tx:13 rx:38 RTS|CTS|DTR|DSR

UART2 works, and 1 doesnt.

How (on the command line) can I disable CD/RI for UART 1 so that its the same configuration as UART2?

Thanks