Same problem here, with either smart splitter and programable splitter:
Selecting star (*) for "any" was not letting items through that connector if those items have been selected for one or both of the other connections ... well, until the last update. Many players did ask for a "overflow" solution cause of that behaviour, and tried to find a workaround solution, more or less successful.
Dealing with that "old" issue (not having an "overflow" solution and working around that), together with the current (changed) behavior, now it's even worse^^ The whole existing belt logistic is broken as far as smart or programable splitters are involved.
=== game situation ===
In my case there is a hughe sorting facility/building, where's a belt/storage for each individual (literaly, 94!) item, including a complex sorting infrastructure, having at least two smart or programable splitters for each item... Due to that infrastructure i was able to send every kind of item to that facility and every item got correctly sorted to the corresponding storage ... until i recognized the full/stopped belt on the other end of the map, which pointed to the fact that something is wrong at the sorting facility ... lol
Now i have to make a decision ...
• Pausing the game until there is a fix or until the behaviour is set back to it's earlier state?
• Setting all 200+ spitters outputs/connectors having "any" by now to 93 individual items which have to get through - let me quick calc that: 18600+ manual selections *cough*
Option 2, to set each of the 93 items for the "all others" connector, is not a solution, cause the number of rules for each connector is limited...
EDIT 2 (2019-08-21)
Problem solved due to a new selectable option "Any Undefined" at all programmable splitters as of Early Access - v0.2.1.12 - Build 103400
Tested with MK5 belts having 20 different items mixed at full workload (720/min)