In Excel or airtable, I can create an equation that allows me to sum or run other operations on a series of data that may include null values. Those null values are simply skipped. In Aha! if any field I use contains a null value, the entire equation fails for me, returning a null value itself.
This makes it challenging to use custom fields which do not need all need to be filled and use them in a calculation without the tedious work of adding a 0 value to all of those which could otherwise remain null.
For my use case, my team wants to use custom fields to estimate effort for frontend, backend, QA, etc. and then use an equation in the List report to add those up to the full estimate. They can already do this with a simple app like airtable, so we were surprised when Aha did not have this capability.