On my Pixel 2 with Android 9 I don't see the maps. I get the list of 6 drop down selections (to 4 maps), but no maps.
Same here on Pixel 2. The dropdown bars are there but doesn't display the images (maps). Also, keeps crashing after the 2nd and all subsequent runs. My phone offered to send all the crash data and sysinfo to you, hopefully you'll be able to fix it.
Otherwise, great and useful app, works well on an older Android 6.0 device.