Revit Revision Bubble Not Appearing?

This is so simple, I debated not posting about it. But because this is the second time this same thing got me, if for no other reason it will serve as a note to myself.

A new user came to me, and could not get the revision clouds to appear. As usual, I went through the "how revisions work" speech, and corrected the revision schedule, which was in fact incorrect.

After feeling pretty good about the quick fix, I went to place her bubble, only to get this error:

"None of the created elements are visible in Floor Plan: XX view. You may want to check the active view, its parameters, and visibility settings, as well as any Plan Regions and their settings."

Ok - another simple fix...  obviously my revision clouds are unchecked in the annotation categories tab, of my Visibility Graphics Dialog. (VG -> Annotation Categories -> Revision Clouds).... But, its checked?!

After turning on all the model categories, it worked. Then a minute or two of scratching my head.. I knew it wasn't a workset issue, or a view range issue... I remembered this got me before... The model category "Lines" was unchecked for that view. Click that back on, and everything comes in 

Cannot Draw Revit Pipe Elbows when upgrading to RMEP 2012?

This was too obscure to not share:

A friend of mine had been working in Revit 2011 on a project. A few weeks ago he was asked to upgrade the project to the 2012 platform. After opening the file in 2012, the only elbows that Revit would draw were 90 degree elbows. Any angle in between greeted us with a big fat “do not enter” symbol.

At first, I thought somehow the lookup tables were not being seen? Nope.

Was the working plane slightly skewed from being parallel to the Z axis? Nope.

Pipe routing dropped the elbow family altogether? Nope.

As it turns out, Revit has a sense of humor. For whatever reason during the upgrade, Revit re-set one of its default settings: Pipe Connector Tolerance.

By definition that setting is 5 Degrees.

Pipe Connector Tolerance: specifies the number of degrees by which pipe connectors may deviate from their specified mating angle. The default setting is five degrees.

However here’s what the 2012 version looked like:

This convenient little guy allowed the pipes to be routed only at angles 75 degrees or greater.

Not sure how it gets reset, but setting this value back to 5 degrees will get you back on track with routing your piping.