Actually it's the camera that doesn't scan. Happens to me every other block it seems. Using LG6. I've learned to swipe to finish so what was scanned is saved. Press home, then scan packs, finish scanning, . Swipe to finish again, then refresh the intinary. All is good after. I've seen several having this issue.
For those still getting the "start travel" crash with the newest update and Oreo:
It has to do with the way Oreo handles notifications, limits background activity, and allocates ram. When the navigation in the app throws a persistent notification up in the bar (turn by turn) it overloads and Android closes the app.
Easy fix for now: Settings --> Apps and notifications --> App info --> Flex App --> App notifications --> toggle app notifications off
That should work for now, until the app is fixed. You won't get the "Delivery blocks available" notification, but those blocks are usually gone by the time you check offers anyway.