In the popup to select the MF did you press the "Refresh list" button? This should trigger a Microflow which uses the a java action to get the list of available microflows in your application. If that doesn't work please check if you have any errors in your console log.
There are a couple of reasons why the microflow does not show up. Only microlows with string parameters or with only one Mendix object will end up in the list. So a microflow with an integer value as parameter or with multiple Mendix objeccts will not end up in the selectable microflow list.
And again as stated the MxModelreflection has nothing to do with the selectable microflow list of the deeplink module.
In Mendix 6, DeepLink and ModelReflection have nothing do to with eachother anymore.
You need to manually refresh the list now, on the DeepLink.Microflow_Select page.