Unable to use field Econa in joomla article.

 I just install the extension Econa and activate all the plugin with the necessary information as described in the documentation in this site.
I create a field type Econa and give size and all settings as described in documentation.
I can use the resizing for intro and full image in joomla article.
But I cannot use the fields Econa with tab in joomla article.
When I click on tab Fields in joomla article, I can view the fields and I try upload from my computer, select it and also from the server and I receive always an empty square in place of the image.
I cannot upload here the sreen capture and I work on my local MampPro test.
I try to use your extension with joomla 3.7.5 and Gantry 5
I use also admintools pro but in my local test it is disable
Can you identify where I can find a solution or any information for identifying what happens with these fields.
Php version 7.1.8 and GD is enabled.
For now I cannot use field Econa in joomla article.
Thank you for your help.

After search in ticket, i see that the extension cache cleaner from regular labs can do problem.
So I change the setting for non-emptying the tmp folder but nothing change, i have always an empty square in place of the image selected from my computer or from the server. When I edit the empty square and want to save it. The message says "No valid image was loaded." but all my images are already on server and are .jpg

So I deactivate the plugin cache cleaner from regular labs and I have the same problem.

I continue my search but perhaps you have a better path for identifying the problem.

Thank you

I have the same problem on a normal server. The directory permissions are correct. I verify all the settings.
I have exactly the same error on my server and on my local site.
I deactivate completely the cache cleaner from regular labs but nothing change.
What can I do ?