Is the problem with copying text in that app, or pasting text into mine? If the problem is with copying from that app, it would be best to ask them about it. They might have disabled the copy function to prevent you from using other apps.
I've tried this a few times. The issue seems to me is that unless you're a paid subscriber, it's difficult to copy from UG.
I've never been able to do it with the iPad or a tablet, and gave up trying in pretty short order.
However, on a PC, you can click and hold at the END of the song, swipe upwards to the beginning to highlight and then right click/copy.
Having done that, open a fresh Notepad document and paste the text into it.
Then Select All, and Copy. By doing this you "wash" all the HTML formatting from the web page off the text.
Then you can paste the "clean" Notepad text into the Bandhelper web interface.
Anyway, it works pretty well for me . . .