Thanks for reaching out. We are sorry for the trouble with Adobe Lightroom on iOS. We are here to help.
Before the update, did you import a large batch of images into Lightroom? Do you use Lightroom on any other surfaces like the desktop or Lightroom Classic?
Log on to Lightroom Web (https://lightroom.adobe.com) to check current Sync issues on the left part of the screen.
If there are any sync issues, click on them to know more, find the original for those images, and back them up safely before you empty the Sync issues from Lightroom Web.
If there are no sync issues, you can try and reinstall Lightroom and let us know if it works.