But then you have to be in sync with the channel settings of the internet provider, at least.
By using station you are tracking the ISP channel setting, the AP uses the same interface setting.
Very typical for a one-radio “repeater” setup.
You need a second radio for your AP functionality. Typical for a 2 band device (2.4 and 5 GHz) you use the other band.
One partly workaround is using a connect list, and always having an SSID to connect to. (I even added my personal hotspot on my smartphone, as one of the SSID, so that the AP function would start.)
http://forum.mikrotik.com/t/auto-connect-to-different-ssids/141473/1