This isn't really related to https://github.com/elastic/eui/issues/1007, since this is affecting initial props. So, if the component starts out with anything other than its default/initial pagination prop eg:
const pagination = {pageIndex: 2, pageSize: 10};
<EuiInMemoryTable
pagination={pagination}
...
/>
I think it's because getInitialPagination does not return anything if pagination does exist:
https://github.com/elastic/eui/blob/master/src/components/basic_table/in_memory_table.js#L95
Maybe reimplementing it to something like this might fix it:
const getInitialPagination = (pagination) => pagination || {};
I'm unable to replicate this issue, can you provide a demo of the bug (e.g. with https://codesandbox.io)?
For testing, I've added
pagination={{ initialPageSize: 4, pageSizeOptions: [2, 4, 8] }}
to the example at src-docs/src/views/tables/in_memory/in_memory.js and get this result:

Please try it with:
pagination = {pageIndex: 2, pageSize: 10};
In some cases we want to initiate/start a table at page 3 for example.
This relates to https://github.com/elastic/kibana/issues/32663, unfortunately angular does not update react components but instead redraws them anytime there is a change from the scope
Ah, gotcha. I mis-read your pageIndex: 2 key/value.
re: https://github.com/elastic/kibana/pull/34565/files#diff-f5c2be5f354e6067ab8d71ff231e2077
I can't see us changing the names of these props (so the mapping in the above PR will need to remain), but it does make sense to support an initial page index.