Welcome to the forums Kent.
A few questions that may help answer your questions. Is it all columns or just a specific column that is causing you problems? If it is a specific column, what is it defined as in Access? And in Monarch? When you say that it has issues when exported to a third party product, is it a specific export format? Have you tried exporting to Excel, test, and perhaps another Access database? Hopefully these questions will help to show where the problem is occuring.
Those fields are defined in Access as number fields. From there I have to change them to character in Monarch for the 3rd party application to accept them. This issue affects about 30 columns in Access. Some of the columns import just fine but for some reason these require additional formatting from Monarch. I will try to export that into Excel to see if that makes any difference. I will keep you posted.
I suggest pulling the numeric columns from Access to a numeric Monarch column. Make sure the lengths of the data match. Then, add a calculated field to convert the numeric column to a text field in Monarch. Since you want a space instead of a null for cases where there is no numeric data, I would say
Hopefully, this will solve the problem for you. You're doing the conversion from Numeric to Text explicitely using Monarch's caluclated fields.