As I mentioned, my data is not clean and cannot be modified. They want to see the empty or invalid characters when they occur. They simply want my analysis to treat those cells as being no data.
Because of this, I cannot use the MAX function as it throws an error on the invalid characters and the min function must not count zeros as a value. That is why I had to write my own UDF's.
I had gone through one spread sheet of data and had it consolidating summaries from each sheet onto a separate cover tab.
But when I moved on to the next spreadsheet, I encountered some of the raw data issues and the errors. That is when I replaced the build in functions with my replacement UDF's. With the UDF's in place, the on sheet summaries functioned properly, although I sometimes had to force the sheet to recalculate. However, that is when I discovered that my off sheet cover tab summaries, that pull data from all of the other sheets were not seeing the data that comes from cells that used the UDF's on the other sheets.
My UDF's are saved in a module, not a code section of a sheet. I can use them on any sheet. But, when I try to use multi-sheet references to cells from other sheets, and the data on those other sheets is coming from cells that use my UDF's, the formulas return zero values.
If I could get the built in functions to work and not throw errors, I would not have an issue.