Box 5a and 5b refers to the lines on your actual 1040.
If you are looking at a summary screen or review screen those show the full amount as income and lump a lot of stuff together. You need to check the actual 1040 and make sure it’s right. For 1099R check 1040, the gross amount from 1099R box 1 is in 5a and the taxable amount is in 5b.
