Yep! that was the issue. They are actually running in parallel! it was just the log noise! Thank you for your help. I appreciate it.

So I tried actually initialize different PhotogrammetrySessions but they do not run in parallel. I get this error [Photogrammetry] queueNextProcessingBatchIfNeeded(): Already running a job... not starting new one. Here is my code : class Pictures23d {     func loop(group: DispatchGroup, _ jobNumber: Int? = nil) {         var session: PhotogrammetrySession?         print("run \(Date())")         group.enter()         print("group enter for job \(String(describing: jobNumber))")         DispatchQueue(label: "\(jobNumber ?? 0)").async { [weak self] in             guard let self = self else { return }             let configuration = self.makeConfiguration()             do {                 session = try PhotogrammetrySession(input: self.processingConf.inputFolderUrl,                                                     configuration: configuration)                 self.delegate?.processingStarted()             } catch {                 Foundation.exit(1)             }             guard let session = session else {                 Foundation.exit(1)             }             let waiter = self.waiter(group: group, session: session)             // Compiler may deinitialize these objects since they may appear to be             // unused. This keeps them from being deallocated until they exit.             withExtendedLifetime((session, waiter)) {                 // Run the main process call on the request, then enter the main run                 // loop until you get the published completion event or error.                 do {                     let requests = self.makeRequests()                     if requests.isEmpty {                         Foundation.exit(1)                     }                     try session.process(requests: requests)                     RunLoop.current.run()                 } catch {                     Foundation.exit(1)                 }             }         }     } and from another class this is how I run it:             let group = DispatchGroup()             var index  = 0             for conf in list {                 let picture23dsession = Pictures23d(processingConf: conf)                 picture23dsession.loop(group: group, index + 1000)                 index += 1                 // Everything went fine                 let loadResult = String(describing: picture23dsession.lodResults)             }             group.wait()

Thank you for your reply, yes I have actually already seen this thread. So the answer in that thread indicates that you can have multiple requests for the same session. But what I really need is to have multiple sessions and run the process in parallel. ( for different sets of images) . Do you have any idea how can I achieve that?

So I had a similar issue, after dismissing a sheet presented on a view, the view hierarchy gets messy and I could see in the 3D debugger that the frame of my button has been moved from its original position . Changing .sheet to .fullScreenCover solved the issue. I believe this is a swift UI bug. Xcode Version : 13.4.1 on iOS 15.5