The issue of the HEC events not being written to the newly created index on the HF is unrelated to the indexing tier. For the sake of clarity, can you confirm that you:
Created a new index
Edited the HEC from Data Inputs and in "Select Allowed Indexes" you removed Main and added your newly created index (i.e. - new_index)
When you search index="new_index" you see no events? You tried running a curl test with the HEC token and there are still no events in there?
Remember, new created index may not be searched by default based on the index configuration and other RBAC setting.
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