WEBIDE code completion not working because of Project settings SAPUI5 version error ?

I have the latest SAP WEBIDE version and I have issue with code completion (it stopped working) as this screen shot:

When I checked the app "Project Settings" to see the SAPUI5 version for the app then I found the following error:

I keep selecting the latest version and saving but it is not saving because when I chevck again I still get the above error:

I am 90% sure the code completion not working because of the "Project Settings" issue.

I also checked the mainfest.json file of my project and the sap.ui5 setting looks correct:

Any help please ? I am facing this issue with many projects .

And it is so weird that WebIDE says "Project Settings Saved" but the error show up again when selecting the ui5 version!