Converting raster to polygons in ModelBuilder using FOR iterator gives ERROR 000622

I am having trouble with a section of a larger ModelBuilder routine. I have extracted all but the offending tools to see if I could get those to work. Basically, it takes a raster DEM and converts it to an integer raster based upon a cutoff value. It then converts the integer raster to polygons using the Raster to Polygon tool. It is at this point that it fails.

The model employs a FOR iterator to go through the DEM at increasing elevations of 10. If I run it through just once (beginning and ending elevations are equal), no problem. But if I iterate it two or more times, I get this error:

ERROR 000622: Failed to execute (RasterToPolygon). Parameters are not
valid.

ERROR 000861: Field: is not valid.

Failed to execute (Raster to Polygon).

A couple of things to add:

1. If I execute it from the Edit menu using Run, it works fine and I get multiple outputs.
2. There are no spaces in the paths to the files. Changed this to the default .gdb with the same problem.
3. The output polygons do not approach the 2.1 gb limit for features I noted in the ESRI documentation.
4. I am running it in foreground.
5. There is definitely data at each stage of the iteration. I tested this by running each level as a single pass.
6. I am using %value% to change the intermediate file names for each pass.

I am at a loss as to what I am doing wrong.