Re: a little help here please, a question about my contact app
I saw another post about this recently--not sure if it was also from you.  The Google Photos app is buggy in this respect.  If you still have the older Gallery app, use that--it works.  If you have the app but don't get the option to use it, then you may have set the default app to Photos.  Go to Settings>Apps>All, select Google+, and then Clear Defaults.  Then try again, this time choosing Gallery.
I already sent a bug report to Google about this via the Google Photos app.  You should do the same, so that they get multiple reports.