Reimport fails 'Failed to reimport [Texture 2d/mesh]'

Using Unreal 5.4.4

I am trying to replace my old texture assets with new ones.

They’re saved in the Unreal project as uassets after dragging and dropping into Unreal Engine and have been linked to perforce as version control. All files have been checked out in version control.

The usual drag and drop into Unreal Engine to replace them gives a
‘Failed to reimport [Texture 2d]’ error.

Neither does Dropping the files into the file structure in Windows Explorer and then letting unreal import.

Reimport gives a dialogue box that it doesn’t know the original source but even when ‘Reimport With New File’ is selected and the file is manually chosen it fails.

The only workaround I’ve found is to Import into a New Folder then Delete the Old Files and select a new file to Replace References.
But that isn’t really practical as I have 370+ files to replace and will expect to continuously replace files during development.

Similar problems crops up when I try to replace meshes.