Thomas Heartman (he/him) | Based on their docs, that's ~/.config/JetBrains/<...>, right?
Deleting that folder and launching idea-ultimate again gives this:
2021-09-09 14:52:46,923 [ 6869] WARN - llij.ide.plugins.PluginManager - id redefinition ([row,col,system-id]: [2,3,"product classpath"])
2021-09-09 14:52:49,739 [ 9685] WARN - arketplace.MarketplaceRequests - Error reading Marketplace file: com.fasterxml.jackson.databind.JsonMappingException: Unexpected end-of-input: was expecting closing quote for a string value
at [Source: (BufferedReader); line: 1, column: 81272] (through reference chain: java.util.HashSet[3097]) (file=/home/thomas/.local/share/JetBrains/IntelliJIdea2021.2/pluginsXMLIds.json URL=https://plugins.jetbrains.com/files/pluginsXMLIds.json)
2021-09-09 14:52:49,788 [ 9734] WARN - l.NotificationGroupManagerImpl - Notification group CodeWithMe is already registered (group=com.intellij.notification.NotificationGroup@4c8901b1). Plugin descriptor: PluginDescriptor(name=Code With Me, id=com.jetbrains.codeWithMe, descriptorPath=plugin.xml, path=/nix/store/igrdv5rq177dg6fd2z1id88v6wvq3z75-idea-ultimate-2021.2/idea-ultimate-2021.2/plugins/cwm-plugin, version=212.4746.92, package=null)
And the same blank window.
| 12:54:09 |