This is an expected behavior. A radio can only operate on a single channel at a time... it cannot alternate between two or more channels. If the device has only a single radio (or if you are using the same radio for upstream and downstream connectivity), it must first establish the 'sta' (client) mode connection so that it can appropriately select a channel (necessarily the channel of the AP it is trying to connect to). Only then can it bring up the AP mode SSID.
If the upstream AP is not in range or available, the radio will not function.
There is a solution for this: Travelmate