I was having this issue (on fb, if that's relevant) and came across this post, seeing no resolve I figured out that holding down in the text area to show the curser, and then pressing the cursor itself brought up the paste button. Hope that works and stuff.
PAISTE ✌ oh and for the record, this is what I was trying to paste, so I felt like it was necessary to paste it here, too. In strict regard to the issue of course.
https://m.facebook.com/LeQubeofficial/
Yep, it worked.
-peace