See image below -
Apparently, the parameter “Design Option” shows up twice in the listing of Room Parameters, and is not always the same value. Also it can change from one run of Dynamo to the next (between a value of -1, the ID of the Design Option, and the Design Option Name in 0.7.5, and values of null, the ID, and the Design Option Name in 0.8). Anyone know why this is happening and how it might be resolved?
Repost of second image
-1 means “no element assigned” (in this case no design options).
Everything else you’re experiencing is related to the fact that the GetParameterValueByName node currently is a broken mess. 
Let’s hope someone takes pity on this node soon as it does seem to be a rather important one… 
Andreas-
Normally I’d agree, but isn’t it true that as soon as Design Options are activated, all model objects get assigned a Design Option value of “Main Model”? See the second image and look at indices 31 and 39 - sometimes they equal -1 and sometimes they equal Main Model.
Apparently it is also tied to this: https://github.com/DynamoDS/Dynamo/issues/3108
Thanks-
“Main Model” means “Not assigned to a design option” hence the -1 value. The root cause of what you’re seeing is that that the GetParameterValuesByName node sometimes returns IDs and sometimes the objects the IDs represent.