I got a new GPS for my Matek f405, and after I set it up and got betaflight to recognize it, I can't get any satellites. It's a BEITIAN BN-220T.
The GPS module can't give you even an approximate position fix until it knows where the satellites are. The satellites transmit this data (called an "almanac") continuously, but it takes about twelve and a half minutes to send a complete copy, and it's only good for a few weeks. If your GPS module has been powered down for longer than that, it needs to wait for an updated almanac before it can do anything.
(Your cell phone can get a faster fix by downloading a copy of the almanac off the Internet, but presumable your quadcopter isn't set up for this.)