Hi Michael,
the fact you were able to use these in previous versions was actually unintended. However we figured that there are a couple of projects out there that were using this “feature”. Thus, there’s a compatibility option: LL_OPTION_COMPAT_ALLOW_INVALID_CHARS_IN_SINGLEFIELDFORMULA with value 319. In .NET, you’d set it this way:
LL.Core.LlSetOption(319,1);
Other languages accordingly - let us know if this helps.