When hovering over a button on anything - be it the reactor terminal, turbine terminal, anywhere that uses tooltips, there is a small black rectangle where the first letter of the tooltip should be, but nothing else. Only other mods installed are AE2 and Phosphophyllite.

Fixed in 6d3408f for Phos. By the looks of it, the conversion to Mojmaps or something turned a getString() into a getContents(), but for Translation components, contents is empty (while string is not). Should be fixed in the next release/alpha.