Microsoft Access (Office 365) - fix report based on Union query

We have a Microsoft Access database where we have an issue with one report based on a Union query. When search is performed (of three tables) the report only displays first 255 characters of the information and the rest is cut-off. It also seems that this search does not return the same information if the individual tables are searched with the same parameter. We need to have this query and report fixed. Basic understanding of Spanish is required as the database is in Spanish.