Material not visible because it was saved without engine version

Hello,

for my game (engine version 4.20.3) i use a pack from the marketplace. Now i have the problem that packinging failed. Problem is that the material M_Glass01_Glow.uasset is not visible in the editor because it was saved without engine version.

UATHelper: Packaging (Windows (32-bit)): LogInit: Display: CookResults: Error: Error loading C:/Users/Uwe Xander/Documents/Unreal Projects/Testprojekt/Content/ModernCityEnvironment01/Materials/M_Glass01_Glow.uasset!
UATHelper: Packaging (Windows (32-bit)): LogInit: Display: LogCook: Error: Error loading C:/Users/Uwe Xander/Documents/Unreal Projects/Testprojekt/Content/ModernCityEnvironment01/Materials/M_Glass01_Glow.uasset!

UATHelper: Packaging (Windows (32-bit)): LogInit: Display: LogLinker: Warning: Asset ‘C:/Users/Uwe Xander/Documents/Unreal Projects/Testprojekt/Content/ModernCityEnvironment01/Materials/M_Glass01_Glow.uasset’ has been saved with empty engine version. The asset will be loaded but may be incompatible.
UATHelper: Packaging (Windows (32-bit)): LogInit: Display: LogLinker: Warning: Unable to load package (C:/Users/Uwe Xander/Documents/Unreal Projects/Testprojekt/Content/ModernCityEnvironment01/Materials/M_Glass01_Glow.uasset) PackageVersion 518, MaxExpected 516 : LicenseePackageVersion 0, MaxExpected 0.

For me it looks like the errors depends on the warnings because there is no engine version in M_Glass01_Glow.uasset but i don´t know how i can fix this problem.

What can i do?

Thank you!
Uwe