Conversation so far:
Can you tell me more about the reformation that took place from 2009-2014?
Eventually, the band appeared for the first time on stage together in nearly five years as presenters at the February 2009 Grammy Awards, announcing their reunion.
What led to them appearing for the first time in five years?
CANNOTANSWER.
What happened after the band's reappearance?
The trio embarked on a reunion tour of North America from July to October 2009, with a European trek following from August to September 2010.
How did the reunion go?
CANNOTANSWER.
What are some important things that happened regarding the reunion?
The recording process for Neighborhoods, the band's sixth studio album, was stalled by its studio autonomy, tours, managers, and personal projects.

Question: Why was it stalled?
Self-contained rewrite: Why was Blink-182's album Neighborhoods stalled?