Stuck at Loading on Initial Install

Anyone familiar with this issue?

I made an iOS app using Unity.

It seems that one some devices, mostly iPads, on the first install the app stucks at loading. But if you close it and reopen the app, it runs fine. And it works fine moving forward. Unless if you uninstall it and reinstall again. And same issue happening again.

But for devices, that works. It works fine. Any ideas what causing this initial stuck at loading?

RESOLVED: I just had a buggy preload script which had timing issues when load and removing the preload screen.