When diving in gauge mode, Suunto D5 works as a bottom timer and does not calculate decompression information.
Therefore, when switching to air/nitrox dive mode after a dive in gauge mode, Suunto D5 does not have decompression information available which is crucial for further calculations and safe diving. As a safety measure the decompression calculation will be available again after 48h.
After 48h all residual nitrogen remaining in our body from previous dives should have dissolved and new decompression time calculations can be started.