Hi @MikeGo ,
Could you share the statistics of the table: how many files it has, what is the average file size?
1. Purpose of OPTIMIZE is to combine many small files. Does you table contain many small files?
2. OPTIMIZE is idempotent - if run twice without any data changes in the table, the second OPTIMIZE won't do anything.

In general, based on this article, the delta.targetFileSize setting acts as a guideline or target for the desired file size, but the actual file sizes can vary based on several factors, including the current size of the table, the nature of the data, and the specific operations being performed: