Here is what I tried and it worked. I hope it works for you as well.

1) Go to Gear > Payroll Settings > Export

2) Click "Turn off export" and select None and continue

3) Go back to Edit Export settings and then choose the program you want to export to. (I chose QB Online) and press continue

4) You should see this header "Set up QuickBooks Online to sync with your payroll account" You will be prompted to log in to sync the export with your choice. Click Sign In after entering your password.

5) You will now see a header that includes the title Actions. Press the "Select" hyperlink.

6) You should now see your linked account and your export preferences. Press Done after you have reviewed your preferences. 

7) Try your export again.

I'm not an expert, just a user, but this worked for me.