Ever since JW stopped working, I've been using the one linked here (for Windows machines). Sometimes it'll miss a small number of icons, but it still takes less effort to go through, delete the ones it caught, and try again.
I just tested it to be sure, using a batch of 31 icons. It missed five, giving me an error which Googling says means the file was in use and couldn't be modified. Not sure why that matters to an upload, but yeah. I deleted the ones that did upload, ran it again on the ones that didn't, and all of the previously-skipped icons uploaded that time.
A bit of extra effort for sure, but JW always skipped a few icons on me, as well, so it's not too bad.