It can be a feature but for me it is a bug. You can no more use Property in Expresions when you change settings of Option Set in Property manager to "Allow multiple choices". It would be useful to still have this option when you want to combine more parameters in to new one in schedules or labels.
When you set the Options Setup Dialog to "Multiple Choices", then if you use the Fire Resistance Rating in the Expression defining the "xxxx" Property, then how should Archicad decide which of the multiple choices you allowed for Fire Resistance Rating should be used when calculating the value of the "xxxx" Property?
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