Hi,
No experience with the U2 here but according to the U2 supported device list (https://melabs.com/includes/compatib...eprog.pics.htm) the 16F1783 is supported.

I don't know enough about the erase/programing algorithms to say but the device list linked to above include a comment for the 16F1783 about requiring variable Vpp while the old 16F886 doesn't so there may very well be differences there. With that said, the device is supported and "should" work with the U2.

I'd try the latest software if you're not already on that. Latest seems to 4.67, from 4 years ago (https://melabs.com/support/progsoft.htm)

/Henrik.