Problem encountered when modeling with Delft3D

Is there someone with experience with Delft3D from Deltares? I'm having a problem with Quickplot when I export a variable into ".mat" file format and try to re-open the exported file in Quickplot right afterwards, it says it can't find the data. Seems like the structure is somehow modified. Anyone experienced the same problem? Ideas on how to solve it?

Thanks in advance and kind regards,

Santiago Symonds, MSc, Eng.