Find your material import project and select "Signature". Png layer, hold down Alt and drag the imported material to signature. Png "layer or choose the lost material" signature "Ctrl+Alt+P" to find the material path again in the project.
The loss of special effects may be caused by the software version or related to the localization of the software. Another possibility is the relationship between 32 64-bit softwares.
Or you really don't have this plugin-
Hand typing