This awesome feature called bulk upload of In app purchase items via csv - available via Application Loader so far, has been suddenly taken away by Apple from XCode 9 and on. I tried some previous versions of Application loaders (2.9.1) but they lacked this feature as well.
Today I had about 50 IAP items and I struggled with command line iTMSTransporter but got no way of working around it any way.
After entering some test IAP products on itunesconnect, I got itms (XML) file but could not upload it back to itunesconnect post adding my other IAP items.
If I skip providing IAP screenshot, it complains about missing screenshot.
If I provide existing valid file name present in the same folder as iTMSTransporter, it comes back with error:
1.png is from the list of files requested by Apple, but it was not found locally.
I have already tried naming it same on portal and my local storage but to no avail.
Why can't Apple make life simple enough for devs paying 30% of their hard earned money?