This button rebuilds the v_{EntityName}_AllFields view for each of the selected entities.
This function understands the dependencies so will for example re-build the contact and company views before requirement etc.. so that the chance of circular references are minimised.
If errors still persist in grids after running this, then the best course of action is to manually select the entities individually in the following order and rebuild each selected view separately:
i. Company
ii. Contact
iii. Requirement
iv. Placement
v. Timesheet
vi. SalesInvoice
vii. PurchaseInvoice
viii. PurchaseOrder
ix. PaymentsReceived
x. PayExport
xi. Task