The variable maxdeg is defined in the mask of the subsystem "Sloshing Tank 1" and is given as a parameter to the block "Gravity EGM2008 ECI", which is defined inside a custom library. Sometimes this error is accompanied by another error which states that the workspace of the masked subsystem is not initialized. I cannot debug the problem because when I try to run a simpler model with the single block "Sloshing Tank 1" or with the block "Gravity EGM2008 ECI" it runs smoothly.
If it may help, the model includes a Simscape Multibody system.
Thank you in advance for your help.