401K and QBI

I'm running some scenarios for 2021 and could use some assistance. I have never had a sole proprietor with a solo 401k. I am inputting a Schedule C net income of $60,000, also has wages of $100,000 from another employer (no retirement plan). Assume taxpayer is over age 50, MFJ, and makes maximum 401(k) contribution allowed. I calculate he would get a schedule 1 deduction for $37,425 for the 401(k), correct? When calculating QBI, I don't understand the income amount the program calculates, which is QBI of $27,885. It begins with the $60,000, deducts 1/2 of s/e tax of $2,877 and $29,238 for the s/e pension. Anyone know how the $29,238 is calculated? I'm totally missing something or have something coded incorrectly. Thanks!

makes maximum 401(k) contribution allowed

Quantify this.

Assume maximum elective deferral and maximum employer match allowed by law (I know would have to go by plan document).

My calculations on ProFX:
Sched C Net $60,000
SE Tax $6,914 (assumes wages subject to FICA & Medicare =$100,000)
Max 401(k)=$37,309 ($60,000-1/2SE $3,457=$56,543*20%=$11,309+$19,500+$6,500=$37,309
QBI $19,234 ($60000-1/2SE $3.457-401(k) $37,309=$19,234

Thank you Ickent! My SE tax was off from yours, and it appears that I had something input in another screen for another scenario I had run (although I could not find the input on the screen). I deleted the client and started fresh and am now coming up with your numbers; those numbers make sense! Thanks again - I'm not losing it!