Please kindly help us to fix this issue
There’s a lot of small geometry in your model. More after using Subtract which will be a problem. Convert the extrusion to a component, copy the extrusion and the cylinders and scale the copies up by 1000x. Then use Subtract from Eneroth Solid Tools or Difference from Bool Tools 2 on the large copies to create the holes.Don’t use the native Solid Tools. After you’ve finished delete the large copy and return to the original one.
You could also adjust the import options to cm, make the edits, then scale the result down by 0.1