Hey tebruno99,
This is a known issue with 4.5 (TTP# 348178 and 346669) that has since been fixed internally. Unfortunately, fix is part of a new Blueprint menu system and won’t make it into engine until 4.6.
In meantime, all nodes should still appear, but you might need to check or uncheck Context Sensitivity to find it. You can also use Palette window in some cases.