Platform: PC
ISP: CenturyLink
Type of Internet Connection: DSL
Internet Connection Speed: 50 MBPS
Date & Time: 08/28/2019
Frequency: Easily reproduced
Character Name: Naomienya
Race: Taru (TT)
World: Ragnarok
Main Job: BLU
Support Job: RDM
Area and Coordinates: Dho Gates
Party or Solo: Solo (5 trusts)
NPC Name: N/A
Monster Name: Apex Bats (might apply to more apex family monsters)
1. Achieve all capacity point bonuses (from job traits) plus quest/mission based bonuses for capacity points plus Aptitude Mantle (HQ or NQ)
2. Achieve capacity chain 10+ (may be lower til you notice the effect, but for sake of argument 10 will definitely show it)
3. Use Trizek ring
4. Overflow wastes the ring benefit

Detailed explanation:
So it seems to me that the variable that stores capacity points earned from a mob is 16 bits therefore a maximum value of 65,535 in decimal. What happens is, when you use a trizek ring at a sufficiently high capacity chain you will be limited by the precision of this value; however, the system counts this against your trizek ring benefit, and thus the remaining benefit is lost due to overflow. I tried this same thing with a normal capacity ring and it seems to not be wasted as I had a couple back to back max value kills. Below is a quick bit of example data I took.:

Prior to any ring effect (no buff):
Chain #10 - 40,713 capacity points earned

Under the effect of Trizek ring:
Chain #11 - 65,535 capacity points earned and ring wears off (confirmed that I received exactly this amount from job points menu before and after this kill)

After trizek ring (no buff):
Chain #12 - 42593 capacity points earned

Taking the average of 10 and 12 chains yields 41,653 capacity points presumed for chain 11 if there were no bonus. Taking the difference from the maximum 65,535 leaves 23,882 capacity points which is noticeably short of 30,000. With a higher chain and the ring used, this problem is worsened.

Capacity ring results:

Chain #13 - no buff - 49,773 capacity points earned
Chain #14 - Capacity ring buff - 65,535 capacity points earned
Chain #15 - Capacity ring buff - 65,535 capacity points earned
Chain #16 - no buff - 52997 capacity points earned
Chain #17 - no buff - 50565 capacity points earned

This seems to be working properly at a glance since two chain kills give the max value, but I'm not entirely sure. I also don't have any other rings (ex. Facility Ring) to confirm or deny this similar behavior. Hope the info helps! Thanks!