I type documents in multiple languages and had no problem before using the Alt + NUM keys to get the letters I needed (á, í. ó, ú, Ñ, ©, Á, É, Ú, ü, Ü, Í, Ó…along with other special characters. Since the last update of LO the use of the Alt + Num sends me to sidebar.
I have used this method since 1977 in all the different brands of office documents with out a problem; now, all of a sudden with this new update to Libre Office 7.6 it does not work.
Use the Customize feature and delete these HotKeys from the LibreOffice scope.
Alt codes are a Windows-only shortcut. Enter the Unicode number and press Alt+X immediately after it, e.g. to get á enter U+00e1 then press Alt+X. If there is no confusion then the code can sometimes be shortened to remove the leading 0, e.g. enter e1 and then press Alt+X to convert to á. The Alt+X combination will toggle between the Unicode number and the character.
Further to @Zizi64 , see [regression] cannot enter alt+number codes for unicode symbols anymore after updating to LibreOffice 7.6.3.2 - #9 by EarnestAl