You would still report this interest income under Schedule C. Even though the LLC is considered a disregarded entity for income tax filing purposes, this will not change business interest income (reported on Schedule C) to personal interest income (reported on Schedule B).
You can report this LLC interest income under "other income" under the business income (screenshot).
Please note: Even though line 5 on the Schedule C says "other income not reported on 1099", it is actually referring to 1099-MISC income only and not interest income (reported on a 1099-INT). So this is the appropriate place to report business interest income if you received a Form 1099-INT.
