For those using One Drive. Feel free to try these quick steps.
-Turn off 'One Drive' and make sure to 'un-sync' any IK Multimedia related files
-In a File Explorer window, go to your Documents -> IK Multimedia -> AmpliTube 4 folder
-Copy any custom presets you have made to another location to back them up
-Delete the AmpliTube 4 folder from the Documents -> AmpliTube 4 folder
-Download the 4.5 update from your the User Area -> My Products section (
https://www.ikmultimedia.com/userarea/) of your IK Multimedia account
-Uninstall, then reinstall AmpliTube to let it recreate your AmpliTube 4 folders
-Now retry your presets and you should be good to go
If these do not help, please as mentioned before. Contact IK support.
http://www.ikmultimedia.com/contact-support/