On May 1st, AWS corrected a long-standing billing bug tied to Elastic Load Balancer (ELB)data transfers betweenAvailability Zones (AZs) and regions. That fix triggered a noticeable increase in charges for many users, especially for those with high traffic volumes or distributed architectures. The problem wasn’t new usage; it was a silent correction to an old error.
What Actually Changed
ELBs are designed to distribute traffic across multiple AZs for high availability. For some time, AWS had been under-billing for data transfers across those zones due to a backend miscalculation. Once AWS patched the issue, affected traffic was billed at standard rates.
Here’s what teams started to notice:
A spike in cross-AZ data transfer costs
Sudden increases in ELB charges, even without changes in usage patterns
No official notice from AWS and no retroactive billing adjustments
Without active monitoring, these increases could’ve gone undetected until the invoice hit.
LogicMonitor’s Cost Optimization dashboard shows a 49.65% jump in networking spend from May 1–14, 2025—an increase (due to AWS’s silent ELB billing fix) of $25.8K compared to early April.
Customers Using LogicMonitor’s Cost Optimization Could See It First
Organizations using LogicMonitor’s Cost Optimization product quickly saw the impact through the billing widget, which provides real-time visibility into cloud spend across AWS, Azure, and GCP. On May 1st, ELB costs jumped, and LM Envision’s Cost Optimization dashboard in various customer instances could spot the change.
Cost Optimization began showing noticeable increases. In several cases, including in our own LogicMonitor instance, customers reported sudden spikes in previously stable ELB charges, often tied directly to cross-AZ traffic.
This scenario was exactly the kind of scenario the LM Envision platform, paired with Cost Optimization, was designed to catch.
By surfacing changes in real time, whether caused by usage changes, misconfigurations, or (as in this case) vendor-side billing updates, LM Envision gives teams the chance to react before surprises escalate into budget risks..
Why It Matters
In an age of dynamic cloud pricing, unexpected billing changes can derail budgets and force last-minute cost corrections. Even minor billing corrections—like this ELB update—can have ripple effects across environments with high traffic or multi-region architectures.
LogicMonitor helps ITOps teams with FinOps responsibilities:
Stay aheadof spend with granular cost visibility
Detect cost anomalies tied to specific services or regions
Alert teams when budgets are at risk of being breached
Enable IT operations teams to act fast and avoid surprises
What You Can Do Now
If you’ve seen a sudden spike in your ELB charges this month, take a closer look at:
Your data transfer patterns across AZs or regions
Load balancer configuration and routing behavior
Any alerts or anomalies surfaced by your observability platform
And if you’re not yet using LogicMonitor to monitor cloud costs and resource changes, now’s the time to see what unified observability can help unlock. When every cloud dollar counts, you need more than reports. You need real-time insight.
See what LM Cost Optimization can do in your environment.
With over 12 years of experience, Ismath is a dynamic product marketing leader known for crafting impactful messaging, executing successful product launches, and driving strategic marketing initiatives for enterprises and growing SaaS companies. A proven collaborator, Ismath excels at building relationships across product, sales, and leadership teams, while consistently delivering high-priority solutions.
Disclaimer: The views expressed on this blog are those of the author and do not necessarily reflect the views of LogicMonitor or its affiliates.
