Copy Monitor Wall Location Line Selection

I mentioned in a previous post that 2016 quietly introduced a parameter that lets us choose which Location Line is important to reference when we use the Copy part of the Copy/Monitor features.

Now that I've been trying to use it regularly I'm running into a quirky situation since installing R2 (I can't say for certain it doesn't happen in the previous version too). When I select a wall it works on the just the first wall. When I choose additional walls I get this warning.

Initially I thought it was happening because I thought it is important to assign the Location Line of the walls in the source linked file to be the same as intended in the host file, but then I don't remember having to worry about that earlier...pause...

Then it occurred to me that whatever Location Line setting I used for the last wall I sketched, in the host model, might somehow influence the process. I tried that and I don't think that matters at all; and it shouldn't in my opinion.

After experimenting a bit further it only works reliably when I use the Multiple selection option to choose all the walls I want to use Copy/Monitor on. I've repeated this using stock content (Imperial) and Architectural and Structural templates. If you'd like to corroborate my findings please try these steps:

• Start a project with the Architectural template
• Create six walls with: Basic Wall Exterior - EIFS on Mtl. Stud
• Use Location Line: Wall Centerline
• Save the file as Test CM

• Using the Structural template link Test CM
• Create a Stud 2x6 wall type (6" because the stud layer in the linked wall is 6")
• Start Copy/Monitor
• Map the linked wall type to the host's Stud 2x6 wall type (in Options)
• Choose Location Line: Core Face: Exterior (in Options too)
• Start Copy and select one wall (no message)
• Select another wall (Error message yes?)

I suspect the nature of wall joins is affecting whatever method they are using to evaluate the wall for the C/M process.

• Use Undo and Start again before using Copy/Monitor
• Set Options again, just to be sure
• Start Copy
• Select Multiple
• Select all six walls
• Click the little Finish button (no error?)
• Click the big Finish button

Earlier I mentioned being concerned about the Location Line setting of the walls in the linked model. I tested for that by starting with walls in the linked model assigned to Location Line: Core Face: Exterior. It didn't make any difference in my testing (see next image). Fwiw, when I first saw this new option appear I did think that was what they intended us to do but Revit just places our version of the wall according to the chosen Location Line position, not according to what the source wall is actually assigned to.

Thinking about it further I realized that if we really could influence this by changing the value in the linked model it should have already been easy for us to use C/M; if they just allowed us to swap wall types based on their setting. Revit was biased to only use Wall Centerline, ignoring the others.

I was nearly convinced that all I had to do was make sure to select the walls using the Multiple option but then in another file it didn't seem to matter or help regardless. Then I noticed any wall I was successful using C/M on (picking them individually) but was touching a wall that generated the error message also needed to be eliminated so I could start again clean. When I used Multiple after getting back to a clean slate I was able to use Copy/Monitor without an error message.

I conclude that the safest way to ensure Copy/Monitor doesn't generate a confusing warning is to isolate all the walls we want to use C/M on and choose the Multiple option. Remember the little Finish button before using the Big Finish button!

Also remember that anytime C/M gets ornery we can just use Stop Monitoring on the affected elements. Fix the problem elements and then use the Monitor part of C/M to let Revit start watching them again.