I hope you have taken a look at the Sample document that I have attached.
I am using more than one reduction field in the Section Access.
The difficulty here is, when data is present in one reduction field, there seems row level reduction to be happening and when value used in other reduction field doesn't present in table, all values are coming.
And yes, I am expecting user can able to enter and seeing no data at all because just some reduction values are not present in table, it doesn't make sense to lose the access, right?
If you want a user to be able to access the app even if there's no data for them, then you need to make sure there always is at least one record for all users. In other words, you need to generate dummy data for all users. If you do reduction on more then one field this can get tricky, but I think it is feasible.
Not sure if it's a working hack for your scenario, but you could force-feed the section access values into the reduction field. There don't need to be any associated values - you just need it to appear in the actual field, so something as simple as:
Do keep in mind that this might impact some objects in your document, so be sure you adjust for that.