Discovered through much pain that echo mode 2 and capslock as fenrir key are incompatible. Documented in settings file.

config/settings/settings.conf

@@ -110,7 +110,7 @@ keyboardLayout=desktop
 # echo chars while typing.
 # 0 = None
 # 1 = always
-# 2 = only while capslock
+# 2 = only while capslock (not compatible with capslock as fenrir key)
 charEchoMode=1
 # echo deleted chars
 charDeleteEcho=True