Will the AF-5500 change the frequency on a GTN650 radio?

Which may bring up another question. I have been trying to resolve a problem with the GTN650. When setting a standby frequency one of the options is selecting from a list of user stored frequencies. When I select that particular option the frequency appears in the standby frequency and then reverts to the previous frequency. The unit was replaced and the same thing happens. At this point I had been assuming the problem was GTN software but after seeing that you now support changing radio frequencies I am wondering if it could be you?