I run a dual boot system - Ubuntu and Win10. Most of my time is spent in Ubuntu so my skills for transferring FF profile data into portable FF are a bit rusty.
Today I made new FF portable app "installations" on the Win10 system. I copied active profiles from the Ubuntu system and pasted them into the Win10 FF portable apps folders.
After making the new portable app "installations" I opened each portable FF so it would populate each iteration's folder structure with necessary FF files. Then I pasted contents of the active profile into the Data > Profile folder of each respective portable FF. Contents of each freshly populated Profile folder was over-written with data from transferred profile.
When testing the portable FF iterations they launched successfully, ran normally, all my settings were there. So far so good.
Although all extensions installed to the profiles taken from the Ubuntu system were still installed their icons were missing from the toolbar of each portable FF iteration. I tried right clicking on a vacant part of the toolbar > Customise but didn't see a way to get the icons back.
I would appreciate any suggestions on how to get icons for installed extensions to reappear on the toolbar.
You need to disable and re-enable them. That will fix the paths in the relevant settings files. The launcher normally does this for you as Firefox Portable moves around but it doesn't know where they came from when you're copying a profile in.
Sometimes, the impossible can become possible, if you're awesome!
When faced with the wrinkle in my profile transfer I was too hasty to post a query here.
I dipped back into Win10 tonight to apply your advice. After launching the respective portable FF iterations the relevant extension icons were lined up in a row in their rightful place on the toolbar. Seems it only needed a browser restart for paths of the setting files to be rebuilt.
I still think you are a legend for conceiving portable apps. Now I know you're awesome too