If you discover one of your categories is missing from the Category dropdown on the Transactions sheet, or the category dropdown box has disappeared from any of your cells in the Category column in the Transactions sheet you will need to correct the data validation for affected cells.
We include steps for how to fix this issue and tips for how to avoid it in the future.
In Google Sheets
Review the location of your Category column in the Transactions sheet and Categories sheet. What column letter does the Category column correspond to in both sheets? The default locations in the Foundation Template in the Transactions it's column D and in Categories it's column A. You'll need to adjust the range references below to reflect the location of your Category column if they are different than the defaults.
In your Transactions sheet, select the entire Category column by clicking the column header letter (click Column D)
Open the Data Menu
Choose Data Validation...
Configure the Cell range to be Transactions!D2:D. Using D2:D, instead of D2:D355 (or some other row number) will ensure that all new rows added get the validation too. You also want to make sure it starts with D2 so you don't include the header row.
Set the criteria. This will always be "List from a range" and in most cases will be Categories!A2:A
How to Avoid this Issue
Do not insert new rows at the top or bottom of the Categories list
If you are pasting manually added transactions into your Transactions sheet, right click and choose Paste Special > Paste Values Only to ensure the data validation gets added to new rows.
In Microsoft Excel
ℹ️ These steps are for the Tiller Foundation Template for Microsoft Excel. If you are still using the Tiller Money Tracker template (it has a "Tracker" tab along the bottom and only a Yearly Budget) these steps won't work and we recommend you migrate to the Tiller Foundation Template.
Starting with row 2 select all the cells in the Category column to the bottom of the Excel table (look for the alternating shading to stop to see where the table ends).
Choose the Data ribbon
Choose Data validation
Make sure the Allow: option has List selected
In the source input =INDIRECT("Categories[Category]")
Leave "Ignore blank and "In-cell dropdown" checked
Click the "Apply these changes to all other cells with the same settings" option
How to Avoid this Issue
Do not insert new rows at the top of the Categories list
Use the next available/empty existing row in the Categories sheet to make sure that the Excel Table expands properly (do not skip or leave blank rows at the bottom of the Categories sheet