Is there a glitch with T3 slip reporting?

Are you looking at the T3 summary page?  That page will show you exactly what was put into box 21. To see the 50% amount that is taxable, you'll need to go forward to the Income Summary page.

No, I was looking at the income summary. I've tried inputting different amounts and it was taking various percentages, but not 50%. Anyway, I've deleted the entire tax return and started a new one. It works now. 

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