Input controls overriding hidden table formula

I have a report I'm working on, where I have a series of tables attached to each other representing 18 months of our business year. Each table is being hidden if an input control of Months does not have the particular months listed, so only the most currently relevant months can be shown at a time.

The Month variable data isn't linked to any of the underlying data in any way.

I have another detail variable used as an input control, which represents staff associated with the row object. They're defined in a separate Excel document and merged with a dimension.

Using the Months input control by itself is great, as it hides the tables, but any time I use the other input control to filter rows by staff, every single table becomes visible again.

Each table, starting from April and extending into September of the next year has a similar formula, so I can select one or many of them. I tried using a date variable actually tied on the data, but it was breaking the cumulative nature of the data.

The formula used to hide the table:

=Pos(ReportFilter([Variables].[Months]); "01 - April Early Engagement") = 0

What would be causing this? How can I prevent this behavior?

Solution

Setup

I created a report based on your specifications:

2 data providers: 1 dummy with just the months, 1 with actual data (in my case a set of dates and amounts
One input control based on the dummy data providers with the months
Another input control based on an object from the other data provider (in my case based on the year of the date object)
3 tables, each with a formula to conditionally hide them based on the dummy months

Remarks

Both input controls have their dependency set on the report, not the individual tables.
The formula to hide the tables is: =Pos(ReportFilter([Col1]); "Apr") = 0 Or Length(ReportFilter([Col1])) = 0

Proof

April and August, only 2014

April and August, only 2015

April and December, only 2015