Not sure what might be going on here, but there have been pasting weirdnesses for me in the past.
Have you tried CTRL-INS instead of CTRL-V?
Another remote possibility:
I only use at best FF52 as a newest version and typically use FF31, but eBay had (has?) some issues with FF31 and paste functionality with seller notes (which I use when relisting or creating listings).
There is a browser setting that wasn't in FF3.6.24 but is in FF31 and caused me trouble.
https://developer.mozilla.org/en-US/docs/Mozilla/Preferences/Preference_reference/dom.event.clipboar...
dom.event.clipboardevents.enabled lets websites get notifications if the user copies, pastes,
or cuts something from a web page, and it lets them know which part of the page had been selected.
The emitting of the oncopy, oncut and onpaste events are controlled by this preference.
If you are comfortable doing so you could play with the FF internal setting for dom.event.clipboardevents.enabled
A shortcut to it: about:config?filter=dom.event.clipboardevents.enabled
That just opens the FF about:config GUI interface to the internal settings, which allows you to toggle the setting and see if that is the issue.
Type or copy/paste that shortcut in the address bar in a new tab, and it will open the settings dialog filtered down to that single setting about:config?filter=clipboardevents.
If that setting isn't present in your presumably newer/newest Firefox version then disregard what follows.
If present, it should be defaulted to TRUE. If you double click on it, it will toggle to false, and the setting text will then be bolded. Leave that tab alone and go try a text paste in a message here and see if that changes anything.
When done playing with it, switch back to the settings tab, double click the setting to toggle it back to TRUE, and close the settings tab.
In the unlikely event that that is the issue, how do you fix it? You really don't.
It's something Lithium should address, but you could use the kludge method I used when the seller note thing was broken. Bookmark that setting shortcut, put it somewhere accessible (bookmarks toolbar or menu), and use it as needed when you need to paste text in a forum message. You use the bookmark to open the setting in a tab, toggle the setting, do your pasting business, and when done, toggle the setting back, and close the setting tab. Klunky but it works. (there is no way to automate the process, and even browser addons/extensions might now have trouble changing settings in new browsers because browser security restrictions. Browser may only allow manual changes - not programmatic)
Probably isn't the issue, but if you have the time and inclination you could try it.
See next message for addendum - ran out of edit time.
