Webview not found by an app (Come it from Xprivacy?)

[esp13]

Hi,
I'm happy with my redmi 3 note pro with xposed+xprivacy+microg+blankstore but unfortunately one app doesn't work.
The app display this message : "Missing System WebView (on android lollipop (5.0+), your device must have the Android System WebView app installed in order to use this app."
I have others webview apps which works great, i checked my restrictions in xprivacy, looks good for me... don't understand why it doesn't find webview. And why is the message speaking of lollipop? (I'm on marshmallow).

Any Idea?
I have an other application that refuse to install on my phone (I'm sure it is compatible with my android version) is there a way Xprivacy provide the android version and if it's not correctly filled it results in this sort of issues?
Can it be microG fault too?

[Toufukun]

Did you unrestrict getPackageInfo, getApplicationInfo or something like that in System category? Or you can whitelist your webview (such as "Android System WebView (com.google.android.webview)") in "Select applications to allow". You can open this dialog in the menu at your app's settings in XPrivacy.

Please check your app's permission Usage data.

[esp13]

All items of the System category are already unchecked.
"Select applications to allow" is gray (not clickable)

But thanks for your help