Employer-plan-based Roth accounts are not Roth IRAs and are not included in determining the taxable amount of a Roth IRA distribution. Employer-plan-based Roth accounts are instead designated Roth accounts in a 401(k), 403(b), 457(b) or the federal TSP. Designated Roth Accounts and Roth IRAs are different types of Roth accounts with different rules.
There is no reason that you could not have rolled over a Roth IRA distribution except in the case where the distribution was a return of contribution, either codes J and 8 or codes J and P in box 7 of the Form 1099-R.
