Clipboard not working with Google Translate website on Firefox Android.

I'm using Firefox 66.0.2 with Android 9.0 on a Samsung Galaxy Note8. I'm trying to paste some text into Google's translate website (also Baidu's). I cannot get the menu to pop up by holding on the screen with my finger or S-pen. When I try to bring up the clipboard with its history using the on-screen keyboard (Default Samsung Keyboard: touch dots on top right hand side, touch clipboard icon) it just instantly goes back to the keyboard. The clipboard works fine with the address bar and www.google.com, and I can copy from other web pages (like about:firefox). Is there some setting I can toggle to get this to work? Granted, for Google translate I can just use their app. Baidu does not have a translation app, though, and their Chinese-English translations are far superior, at the moment.