inconsistent TablixHeader.Size in Report Builder 2

Question

I get this nonsensical error seemingly randomly in Report Builder 2.0. Does anyone know why it comes up or how I can get rid of it?

The TablixRowHierarchy in tablix 'Tablix1' contains an inconsistent TablixHeader.Size in one or more of the TablixMembers that contain headers for TablixRow 2. TablixRow 2 has an expected total header size of 314.959993338585mm and an actual total header size of 314.960003936291mm. The total header size for each TablixRow created by the TablixRowHierarchy must be equal.

Answer 1

I found that I got this error when merging cells in a row in the grouped rows section. If you do not merge all the cells up to the data columns, you get this error. If you unmerge the cells, or merge all cells up to the data columns, the error dissapears.