I'm having trouble reproducing your issue.  If I set the minimum earning level higher than what my GPUs can earn ($10 for example), the Profitability grid is blank (because all the estimates have been filtered out since they are below the minimum) and nothing is mined. If I revise the Minimum Earnings Amount to a more realistic level ($2), then the profitability grid shows only those algorithms that have an estimated earnings higher than that amount and will mine whichever has the highest value. If I set the Minimum Earnings Amount to 0, then I see all enabled algorithms that are supported by the pools I am currently using.

The same thing happens with the CPU. If I set the Minimum Amount to $1.25, the software won't use the CPU because there currently isn't an algorithm that offers that kind of a return on an i7.  However, if I lower the estimated earnings to .25, then there are a couple of CPU algorithms that have higher estimated earnings and there were not any problems mining those algorithms on my machine.

I should point out that the Minimum Earnings Amount only prevents an algorithm with a low estimated earnings from being mined in the first place, but it is not used during mining to stop the current work. You may occasionally see the estimated earnings for the current mining job fall below your minimum amount.  This can happen if the device's current hash rate is below the device's benchmark and historical rates for that algorithm.  The software won't stop mining that algorithm when the price falls below the minimum amount because those dips are usually temporary. You would most likely lose more profits stopping work and switching to something else when your estimated earnings dipped below the minimum for a minute or two than if your cards just kept mining the algorithm despite the lower than expected rate.