Looks like theres a bit or confusion between R10 (intial document check) and Eligibility.
R10 checks that you submitted all your documents and that theyre complete in their given placeholders.
Eligibility actually verifies the contents and reviews whether what you said actually makes you eligible for the class you applied for (CEC in our cases).
As far as R10 is concerned, your reference letter for work exp could just say 'applicant works at starbucks' and nothing else. R10 will mark it as complete.
For eligibility, the officer will actually review the letter, check whether its a real job, whether the Noc code is 0 A or B and whether the job duties you performed match the ones in the noc code.
If your letter is missing duties, officer wont be able to verify you actually performed the job. If your duties allign better to a different noc code, it will also be marked as a red flag. Both of these cases will get your eligibility = not met if removing the job exp takes you under the lowest scoring crs invitee, or if it was your only work exp and now you have none.
Hope this helps.