Can't paste an image into an email signature

I have been trying to insert an image into my email signature on my iPhone 13 Pro (iOS 15.5). It should be something very simple to do, and I have done it previously, as one my emails currently has a signature with an image for my company. I have the image saved to my camera roll and I copied it, went into my email signature the option to paste does not even come up!?! I am very frustrated with this and have spent way too much time trying to figure out something that should be incredibly easy. Anybody else have this issue? Anyone have a solution?