I haven't seen this issue with LR Mobile on my iPad Pro (same versions as you), but I did have this with other Adobe mobile apps such as Photoshop Mix and Adobe Sketch. In each case, the app launched and crashed. If I used the app switcher, I could see it, even with the images showing in the switcher, but bringing it to the front crashed repeatedly.
However, in all cases, restarting the iPad solved the issue. I haven't seen this persist across a restart.
Sorry this isn't much help for you, but I just wanted to provide it as a data point. Perhaps if you force quite all open apps (swipe upward from the app switcher screen) and restart the iPad?