How to paste a link copied from a webpage on Firefox into Proton Mail in order to send the link to someone

I have Proton Mail and I use Firefox, I used to be able to simply copy a link in Firefox that I wanted to share with someone by emailing them the link in Proton Mail. Then that simple process no longer worked. However I recently discovered there were two shortcuts I could access in Firefox to copy the link and then open up a new email and click a paste icon in Proton mail and the email link would be pasted in the email. Now that does not work! What gives and how can I do this process that used to be so completely simple??? Mary Mooney [edited email from community support forum]