I just encountered a very weird behaviour with Firebase dynamic links. It works perfectly on all of our test devices except for one.
This specific device is an iPhon
The overall diagnoses here is that Universal Linking is not configured properly on the device. If Universal Links works on all other devices, then it is probably the case that the AASA file is not being downloaded properly. iOS 11.2 has had issues with this recently.
I suggest that you check the device logs when installing the application to see if the AASA file is being downloaded properly.
1) Delete your app and plug in the device to your computer
2) Open up Xcode and navigate to Window > Devices & Simulators
3) Select the device in the left-hand menu
4) In the bottom of the window you should see a triangle in a box. Clicking this will bring up the device logs.
5) Use a cmd-f to search for applinks
and if your app downloaded the AASA correctly. You should see something like
Added service 'applinks', appID 'RXXXXXXXP.io.branch.Branchsters', domain 'branchster.app.link'
If this is not the case, then it looks like you AASA file is not being downloaded and you may need to delete the app, restart your phone, and try again.