Exclude selected items from select_one list in repeat group once they have been selected

1. What is the problem? Be very detailed.
I have a list of assets to be audited. The process is to select an asset from a list, capture some information, and repeat until all the assets have been audited. Once an asset has been selected once, it should no longer appear in the select one list. I have achieved this by modifying a form from a sample by @LN and including a choice_filter. This works fine, each time an asset is selected, it does not appear in the next repeat. See the attached form test_list.xlsx. I would like to do this using a csv file and creating the list using the search() appearance because I have a large number of assets which will be filtered in the select_one by an earlier room selection. The list changes regularly, hence the requirement for a csv file. My question is can both the choice_filter and the search() appearance be used together? I have tried it without success.
2. What app or server are you using and on what device and operating system? Include version numbers.
A modified Collect 1.22.
3. What you have you tried to fix the problem?
I have created another form , test_list2.xls to do this with the temp_asset_register.csv file.
I have now tried the same thing with select_one_external but cannot replicate the functionality I achieved using select_one. (example attached as select_one_ext.xlsx and intensets.csv). Has anyone been able to resolve this problem using XLSForms?
4. What steps can we take to reproduce the problem?
Run the first form - it works fine, run the second form, it does not
5. Anything else we should know or have? If you have a test form or screenshots or logs, attach below.

test_list.xlsx (20.2 KB)
test_list2.xlsx (20.0 KB)
temp_asset_register.csv (2.2 KB)
test_list_ext.xml (3.0 KB) itemsets.csv (492 Bytes)

Not had many responses here, but I would still like some assistance if anyone can help. I was expected the external choices to work in the same way as internal choices, but it does not. When I run the converted xml from test_list_ext through Validate, I do gets some warnings as follows:

XForm Parse Warning: Warning: 1 Unrecognized attributes found in Element [input] and will be ignored: [query] Location:

Problem found at nodeset: /html/body/group[@ref=/test_list_ext/asset]/repeat[@count= /test_list_ext/asset_count ][@nodeset=/test_list_ext/asset]/input
With element <input query="instance('asset_list')/root/item[not(selected( /test_list_ext/so_far_outside ,name))]" ref="/test_list_ext/asset/choice"><label>

I am looking for help deciphering that please.

Hi @Paul_Storry,

Did you get your solution? If yes, can you please share here your solution?