What might cause such hassle? Any hint welcome

Installed and activated googlemaps at network level. Now when trying to do the settings, unluckily after clicking on google maps window pops up then disappears... only save button stays.

Wondering, what might be the reason for that and where to look at to solve that issue. Would be appreciated hearing from you soon.

Thanks

BTW all other installed plugins work fine also allow to change settings so this case is a one-off bug [reset of cache and permalink done, as wells as de//re-activation of all installed plugins]