On Windows 10 with FF 75.0
After just now moving the entire Firefox Portable to a new location, customizations are missing from the toolbar and menu bar (I use a lot) and extensions don't appear in the Customize Firefox page. Extensions are listed correctly on the Add-ons page but they have no icons. I do have full access to my bookmarks and history.
Moving the program back to the original location restores everything but I don't want it there anymore.
What's the version of the FirefoxPortable.exe file from its properties in Windows Explorer? If you let Firefox upgrade itself, you may be using an older version of the launcher that doesn't support the current version of Firefox's additional settings to allow it to move extensions properly.
If it's older than 2.1.999.0, you'll need to upgrade. To upgrade, download the current version of Firefox Portable 75.0 from our site and install it right over your current version in the old location as described on the support page. Then you can move it to the new one and your extensions should continue to work.
Sometimes, the impossible can become possible, if you're awesome!
'Re-upgrading' Firefox worked, thank you for the prompt instruction on how to correct the problem.
(This is a reminder to be stout of heart and carry on with my intention to manage upgrades on my own terms. Fairly often I find that Firefox has upgraded itself, even after I've declined its offer to do so. I used to go back and re-upgrade with the paf.exe but have wearied of that extra step.)