The problem still exists for "Size to Fit" in LabVIEW 2017. I think that the problem is with the different alignement and resizing policies of the cluster and the elements inside. However, the engineers at National Instruments designed a workaround, which can be considered as a solution for this problem (thank you developers):
For the cluster (which contains the Enum strict type definition and the Variant) choose AutoSizing > Arrange Vertically (or Horizontally, if it is better for you). After that, whenever you create a new constant from that control, it will resize in the desired way (i. e. the Enum and the Variant will remain aligned).
If you originally created your control with the "Size to Fit" option (which is selected automatically), and created some constants from it, and then you changed the autosizing policy of the control to "Arrange Vertically", then you have to choose "Arrange Vertically" manually for those constants.
Also, be careful: for clusters, the "Size to Fit" is selected automatically; do not forget to set it to "None", "Arrange Vertically", or "Arrange Horizontally".
