Start_index and items_per_page not working for appointments

Hi,
I’m trying to get the data about appointments, for example Im using python requests library to send GET request:
https://api.companieshouse.gov.uk/officers/R1c3pcyBVf9jdv8wioWJNx2m0hU/appointments

url to web page:

in the response from API I see 35 items from 45, so only results from page 1 as it shown on web page.
I tried to use parameters start_index and items_per_page, however the result from the api was always same (first 35 items) could you please help me to understand what I’m doing wrong?

for example I tried:
‘/officers/R1c3pcyBVf9jdv8wioWJNx2m0hU/appointments?start_index=0&items_per_page=5’
‘/officers/R1c3pcyBVf9jdv8wioWJNx2m0hU/appointments?items_per_page=5&=start_index=0’
‘/officers/R1c3pcyBVf9jdv8wioWJNx2m0hU/appointments?items_per_page=35&start_index=35’
‘/officers/R1c3pcyBVf9jdv8wioWJNx2m0hU/appointments?items_per_page=35&start_index=36’
‘/officers/R1c3pcyBVf9jdv8wioWJNx2m0hU/appointments?items_per_page=100&start_index=0’
and so on, but I always get first 35 items in api response, please help.

I have just run
curl -u : https://api.company-information.service.gov.uk/officers/R1c3pcyBVf9jdv8wioWJNx2m0hU/appointments?items_per_page=50&start_index=0

and got back the full 45 results
there is also some discussion here

that may help