Comment 9 for bug 1552895

I can confirm that I've the same issue as well, when 2 conditions were met: most of Horizon js files were uncompressed (compression enabled and offline, but the files themselves excluded from compression in _scripts.html file) and Horizon were run by PyCharm in Debug mode. But even with these 2 conditions I wasn't able to reproduce the issue steadily :(.

My impression is that it's somehow related to loading timings, but cannot say more due to the difficulties with reproducing it.