Hello,
while installing the ImDisk Toolkit from the addon section, you can, as a workaround, re-run the installer of Sandboxie-Plus, and check the box to install (or update) the ImDisk Toolkit.
The installer bundles the ImDisk Toolkit for some time, probably to make it easily available as optional component and potentially update it with newer Sandboxie-Plus releases.
Thanks for mentioning that there is a problem with the Addon installation in that regard and thanks for supporting the project.
Thank you for trying again.
I had installed the ImDisk Toolkit with a previous installer of the Sandboxie-Plus 1.17.x version. Before I replied I checked if the addon manager shows it to be installed, which was the case. I also tried installing other addons (SbieHide and LogAPI.dll), what also worked, as well as their removal.
Please mention what version of Windows you are using.
Is someone else on here, who does not have installed the ImDisk Toolkit, able to install it via the latest installer or the addon manager?