thank you for your report. You're right. I recently updated old AmiKit X to from 10.5.3 to 10.5.4. But I forgot that the XE 11.0.0 script is counting with 10.5.3 version as the latest. I will fix it as soon as possible.
Meanwhile, please edit the following file: AmiKit:Prefs/Env-Archive/AmiKitVersion
It contains 1054
Please change it to 1053
and Save and reboot.
Then the amikit_upgrade1100.zip in RabbitHole will get installed. Please let me know how it worked.
Thanks and sorry for the inconvenience.