Line of nodata pixels occuring when running Slope command

[Alex1]

Hello

I'm having an issue using the Slope tool to generate a percent slope raster from a DTM - it is producing a seemingly random line of nodata pixels across part of the resultant raster. The line is not there in  the original DTM and only occurs in this one location.

Any advice on how to prevent this would be much appreciated! 

Thank you

Edit: I have found a workaround for this problem - using QGIS to generate the Slope raster! However if anyone knows what causes this type of error, I would still be interested to hear.

Edit 2: As per the 4th image, the same error occurs when reclassing the slope raster, though now with just a single line of pixels. It is as if ArcGIS simply cannot do raster operations along this specific line. 

[SteveLynch]

I do have some questions:

1) what version of ArcGIS are you using?

2) how many columns and rows does the raster have?

3) what type of raster, Esri grid or .tif or .img or FGDD raster or ?

4) use CopyRaster, with output to default FGDB, does the output have the line?

[Robert_LeClair]

Are you using a single raster dataset or a mosaic dataset for the DTM?