Software bug on the panel signature

What I was trying to figure out is how are you inserting special characters or accents.

If I am not mistaken Adobe changed a few keyboard shortcuts. There could be preferences settings in Acrobat that may trigger undersired behavior if certain mouse or keyboard gestures are employed to insert accented characters (or special characters).

In my personal case, for instance, I am using a Microsoft Windows 10 computer with a generic US keyboard layout (101-key or 104-key). Such keyboards are not localized in another language type nor they provide keys with special characters or accented characters in another language other than US English.

With other Microsoft Windows machines I also use standard "International" keyboard layouts (102-key or 105-key), which are also localized in US English language. 

In both cases above,  I have to employ keybaord combination shortcuts in order to get the desired accented characters or special characters.

See this link for reference: http://www.columbia.edu/itc/french/matheis/1102fa01/edit/accents.html

So I would assume that, based on this other link: https://helpx.adobe.com/premiere-elements/using/default-keyboard-shortcuts.html , you may need to check if there is any Acrobat Preferences setting that need to be disabled or enabled.