The file format compatibility is not necessarily linked to the engine version: we regularly change/optimize/fix issues in the data structure of the sbs file that breaks the compatibility.
In the case of the 2019.2 we have transformed (among other things) the "split points" to "dot nodes".
It is technically possible to "revert" the file format when your file does not contain any element that should be affected by the format update. In such case you just have to change the file version and updater version in the header of the sbs file (just open it in a text editor).
You can open a 2019.1 file to see what value you should use.
Do that at your own risk
