This is what Octotree typically looks like, it's neat!
Going over to the Issues, then Boards page renders no content however...
Reloading the page does load Boards properly. Disabling Octotree also allows Boards to load as usual.
I logged a couple of issues for this problem. First over at GitLab before I knew it was an Octotree problem, then over at the Octotree GitHub Repository. As it stands now we may have to wait until GitLab integrates Octotree as a default before this all works again.
FYI this was with Octotree 2.0.17 running in Safari 10.0.3 on macOS Sierra 10.12.3.