Modifying a projection in ArcPro, and it fails to draw.

Using South America Lambert Conformal Conic and changing the central meridian. Coordinates at the bottom of the map window work fine in the original, after modification, latitude coordinates change to <Null> ºN (longitude still works fine), regardless of where you move the mouse. Thoughts?

Original:

Latitude Of Origin -32.0

Standard Parallel 2 -42.0

Standard Parallel 1 -5.0

Central Meridian -60.0

False Northing 0.0

False Easting 0.0

Linear Unit Meter (1.0)

Authority Esri

WKID 102015

Projection Lambert Conformal Conic

Projected Coordinate System South America Lambert Conformal Conic

Modified:

Latitude Of Origin -32.0

Scale Factor 0.0

Standard Parallel 2 -42.0

Standard Parallel 1 -5.0

Central Meridian -69.0

False Northing 0.0

False Easting 0.0

Linear Unit Meter (1.0)

Authority

WKID -1

Projection Lambert Conformal Conic

Projected Coordinate System South America Lambert Conformal Conic 1

This is a bug. It's fixed in 2.1. Note the additional parameter that showed up:

Scale Factor 0.0

Oops! Change this to 1.0, and the coordinate system will work properly.

Melita

tl;dr; AKA Geeky explanation:

Esri's Lambert conformal conic (LCC) algorithm is "overloaded" to support two variants. One variant uses two standard parallels (plus a latitude of origin). The other variant uses a latitude of origin and scale factor plus one standard parallel. The latitude of origin and standard parallel 1 need to be equal. Similarly, if you end up with standard parallel 2 in the definition it also needs to equal SP1 and lat of origin in this second variant.

For the already defined projected coordinate systems that use LCC, we only show the appropriate parameters. When you create a custom one from scratch or modify an exsting one, we don't know which variant you want so you get all the parameters. In this case, we weren't setting the scale factor parameter to the correct default of 1.0.