Appointment slot not being displayed when it should

Hi.

I have added custom code created by Jose to the latest version of the appointments+ plugin as found here and my client noticed that one of her 90 minute slots is not being displayed when it should be. This problem existed before I upgraded to the latest version as well, so it's not due to the upgrade. The customization allows for 30 / 60 / 90 minute slots to be pushed forward when 15 minute breaks are taken (as in the original post here). The problem seems to only affect the 90 minute slot as far as I can see. You can see in the attached image that a 90 min slot should exist at 2:30 but it is not showing up. I suspect this is due to the day starting off at a 15 minute offset and that trickles through the 90 minute calc leading to no time found. If I open up the schedule until 4:15 the 2:45-4:15 90 minute slot shows up. Any help would be great.