It looks like Ohio enacted Marketplace Facilitator law that goes into effect 8/1/19, and eBay will be required to collect the tax for any sales to Ohio starting then, but that shouldn't be your issue now.
App has many issues, and concerns about the app are best addressed in the app forums.
I created a pair of drafts, edited them in bulk, added sales tax collection for California in bulk, that went fine, and sent them "live" as scheduled listings. When I revise those scheduled listings, the sales tax is there. No reason to believe if I had sent them live directly that it would not have worked.
So not sure what your problem is, but adding sales tax in bulk to drafts isn't completely broken.
I'd have to say it might be a browser issue. I use Firefox 31 and it works.