Hi @tructran
I had run into this issue before. The root cause was the underlying dataset.
In my case I had the following:
a. Dataset 1 based on Custom SQL
b. Dataset 2 based on Custom SQL ( Table 1) and Dataset 1 (Table 2)
When this is the case where you have join with another dataset bincremental refreshes are not allowed. You end up with a full daily refresh.
Refer this thread