Here is a GeoTIFF (single-band) that could be successfully loaded into QGIS but produces no visual output regardless its style settings/parameters. The file can be found here here. Other GIS (e.g., ENVI) could load and display the same file with no problem. What is the problem with this GeoTIFF file? Is it in a format that is currently not supported by QGIS?
[Original question] The "complex type" GeoTIFFs cannot be opened/displayed by QGIS. The image is opened without error message but nothing is displayed. In addition, all the pixels values of the image are indicated as "nan" by the "Identify feature" tool. This GeoTIFF type is characterised by the fact that every pixel is a complex value. This type is handled properly by Python/GDAL, IDL/ENVI... Similarly to ENVI, the absolute value of every pixel should be displayed, and the "Identify feature" tool should indicated the couple of Real and Imaginary values related to the pixel clicked. Please find here an example of complex GeoTIFF that can be properly displayed with other GIS softwares (like ENVI). Handling this file type with QGIS would be very useful as many SAR images are stored with complex values.