This issue may have been addressed but I couldn't find the reference. I'm using 1.9 and working on a plugin based on the Create Plugin docs:

http://manual.b2evolution.net/CreatingPlugin

When I put my stripped down test plugin in the /plugins directory, the plugins page on my back office doesn't render properly. It truncates about 1/2 way through or there are no plugins listed.

When I remove my test plugin or rename it without a leading underscore, the page renders just fine.

What's going on?