Spotlight error with Automator Application - any advice?

Hi,

I have a few really simple automator applications & workflows that run perfectly on my Desktop but refuse to work on another internal drive.

I get this error when running Automator apps on files & folders on some drives…

Here’s an example of one of my Workflows…
Get Folder Contents > Filter Finder Items > Move Finder Items to Trash
As I said, really simple.

After a bit of Googling I think it may be a Spotlight issue, as the files & folders on which the Workflow fails are on drives excluded from Spotlight searches under the ‘Privacy’ tab in Spotlight’s preferences. I’m guessing that Automator relies on Spotlight to fill in the gaps in some workflows (maybe someone could confirm that?) but I need a workflow that does not do that.

I can’t have Spotlight indexing some drives as they are for recording and editing audio. If I let Spotlight index my audio drives it can (and does) randomly crash apps I’m using when it fires up in the middle of critical recordings. Plus the automator app is often used immediately after recording, so Spotlight may not yet have indexed the files I’m referencing (they are huge files and there are plenty of 'em).

Does anyone know of a solution?

Model: Mac Pro 2010
AppleScript: 2.7
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Operating System: macOS 10.14