Some hours ago i opened "tweak" application to change the desktop theme and i was looking for others ways to get a pretty desktop... I activated desktop icons and change some fonts, after that i enabled some extensions and i saw "Activities" name from top bar did not appear. I believe it would be related with "Application menu" extension that throw me an error after enabled him (i did not see the application bar at this moment, it was some minutes ago when i saw the issue) "Error to charge the extension" (translated from spanish).
I have restarted the os and disabled all extension with the general option on "tweak" application getting nothing. I installed an extension after that because i thought maybe it would be an extension i uninstalled "Gnome Global Application Menu(HUD for Gnome)" or maybe it would help me to recovery the name on top bar. When i installed the extension the name appeared again but i saw that the extension was not for that (it added some other options to the menu) but i could be the names again. If i disable this extension and restart the system, the name does not appear again but i do not need the extension for nothing and it is annoying.