Resolve an error for our little iPhone App

Hi all there, We have a small e-learning tool, which uses a synchronization of files between Dropbox and our app. The app is published through app store, but now we want to upgrade it, resolving errors like this: In our app, We have a functionality for listing of all of the files, placed in the users Dropbox account, which are our files (extension - .pau files). The problem is, 1. That we are becoming false sync - in details - when we select one of the files from the list to sync, we are becoming another file synced in our app - real file, but other file, which means, that the listing of our Dropbox existing files is making us errors. 2. Sometimes, we become false listing of the existing files in the users Dropbox account. 1. and 2. - are because of the false working of the listing of our app. Details: - You will work on your tools like XCode to resolve the problem - we only accept .zips, in case need you will receive an access to our dedicated machine through TeamView. - You will receive a shared editable link from dropbox folder to copy the directory structure, which is making the error and simulated under your account and to test in your own. - You will receive a source to work. We work with XCode 9.2, Swift 4.0. Please, see the 5 steps snapshots attached, to understand better the simulation of the error. For our testing purposes we use 3 Testers with real devices, and one simulator. 1. Please, place a bid, only and just only, when you not hurry up, because we need testing. 2. Please, place a bid, only in case you think that the bid will not increase 70 $, bids over 70 $ will be strange. 3. Please, place in your bid 14 day working time. 4. Please, we are uploading and testing always through the official TestFlight of iTunesConnect, we will declare you as a developer for that testing purposes. Thank you. Newcomers are welcome!