Tab group name does not appear in Toolbar immediately after FF launch

[Cbhihe]

Hola Luís

[Personal note: I read your note on why you will be stopping dev work on your add-ons from November 2017 on. Really sorry to see you go. Most of us understand your decision entirely, however hard it is to accept it in my case, because I use TabGroup daily in my work and personal browsing. Thanks for all the incredible work you have done... y que vaya todo muy bien en tus futuras andanzas.]

Issue:
I run FF 53.03 (64 bits) on Ubuntu 14.04.5 with TagGroup v.2.1.4.
Everytime I launch FF no tab group name is displayed on the tool bar. No matter how much I click on the spot where it should be, the only way to make it appear is to enter the mode "Customize Toolbar" and immediately exit that mode without doing any customization at all. Only then does the last used Tabgroup name appear and everything functions normally. It's weird and looks like a bug to me, inasmuch it is systematic and occurs every time I launch FF.

I have not seen any report on this anywhere, hence this note. Cheers. -ced