If you have named sets that reference tips, the default value of 1 protects those tips from deletion. So, even if you try to delete all the tips, PC-DMIS keeps tips that named sets explicitly reference. However, this default value does not protect tips from a non-explicit reference. An example of this is a set that uses all-tips-with-defaults but doesn't have explicit references. Deleting that tip component still removes all tips.
If you want the older traditional behavior of not protecting tips, you can set the value to FALSE (0).
Entry Name: ProtectTipsUsedInNamedSets
Entry Type: Whole Number to specify TRUE (1) or FALSE (0). The default value is 1.