Using External file ref with Index and Match

I cannot make an external file ref work with either Match or INDEX. For example I have this:

 =MATCH(B5,a4:a10,0) it works

But as soon as I replace the range with an external reference it doesn’t, I get N/A. The value is definitely in the external range. To insert the reference I go to the external file, highlight the range and select it.
The file ref looks like this:

'file:///C:/Users/Liz/Google Drive/Temp/FileName.ods'#$'Process H'.O387:O390

I read something that suggest a null string ("")added to the end might help but it doesn’t. Do I need to do something else to this reference?

Thank you

Even more confuded now. I was trying simple stuff and tried to select one cell on an external sheet - using a mouse. The value in the cell was:

=‘file:///C:/Users/Liz/Google Drive/Temp/FileName.ods’#$‘Process H’.O387

The value in the source cell is ‘10 Red’, The value in the calculated target cell is 0

Am I going mad?