I spent several hours trying to get this resolved last night, and could not find any solutions ANYWHERE. So I'm here, and hoping someone here can actually help with this.
Using Linux with Pop! OS, was successfully able to install Minecraft and Forge version 1.12.2. Everything is there in the system, but I'm trying to access a server that uses a newer version of Minecraft. So, tried to use the same process to install 1.13.2 and 1.14.4, and have the same issue with both newer versions.
When I go into my profiles list and try to change my Forge profile to use a version of forge newer than 1.12.2, it just isn't on the list. I can see the grand history of every Minecraft version, and the Forge 1.12.2, but no newer forge versions.
I've tried re-installing several times, both 13 and 14. Ran with and without sudo permissions, no difference. I have no antivirus or anything else that would be blocking internet connection to download the files. No error messages, it seems like it installs properly. Also including the installation log for reference.