I'm having trouble with a workflow that is being used to validate data from a pension scheme.
The benefits are split by period, in the snip below, the blocks are "Pre 1988" and "Pre 1997"; the filter tool is checking entry date against the benefits to make sure that the start date / leave date of the member is consistent with their benefits.
The 1st filter rejects members who have benefits labelled as "Pre 1997", but joined the scheme from 1998 and onwards so shouldn't have any Pre 1997 benefits.
Each of the output tools appends the records to an output file created earlier in the workflow
In this case checking the message log, the output file has been created and the Pre 1988 failed records have been written to it.
Last time I ran, the opposite was the case, only the Pre 1997 records had been written and the ! error was on the Failed Pre 88 output tool.

Sometimes I get a "unable to open the file for write..." on the "Failed Pre 97" tool, sometimes on the "Failed Pre 88" tool.
This suggests that the file isn't being closed correctly after the initial creation or on the 1st append.
Is there a way to "force" the spreadsheet closed to ensure that it is available to be appended to at the relevant stage of the workflow?
Or do I need to change the "flow" of data somehow?