Agencies monitoring AI visibility for clients have a new anomaly to explain this month: Google's AI Mode, after switching to the Gemini 3.8 Flash model in early September 2026, largely stopped showing source citations. Google has confirmed it's a bug, not a change in how citations are evaluated.
The timeline
Google introduced Gemini 3.8 Flash into AI Mode on September 1-2, 2026, for Google AI Pro and Ultra subscribers - the third Flash-model rollout in six weeks. Within days, marketer Gagan Ghotra published dozens of AI Mode queries returning zero citations, and analyst Glenn Gabe followed with a side-by-side test showing the default model citing sources normally while 3.8 Flash produced none.
Barry Schwartz reported the story on Search Engine Roundtable on September 3. On September 4, Robby Stein - VP of Product for Google Search - confirmed it directly on X: "This isn't working as intended, and we'll roll out a fix soon." No fix date was given.
Why this matters for agency GEO monitoring tools
If your monitoring stack tracks AI Mode citations across client accounts, expect a visible dip starting the first week of September 2026 that doesn't correspond to any actual change in the tracked pages. Before flagging it internally as a client-content issue or escalating a false alarm, check whether the affected accounts are on Google AI Pro/Ultra - free-tier AI Mode runs a different model and isn't affected at all.
This distinction matters when reporting to clients: a citation drop tied to this bug requires a very different explanation than a drop tied to actual content or ranking changes.
What to tell clients right now
- This is a known, Google-acknowledged bug affecting one specific model, not a permanent shift in how AI Mode selects sources to cite.
- No content changes are warranted based on this data point alone.
- Continued investment in structured, directly-answerable content, clear expertise signals, and up-to-date data remains the right long-term GEO strategy regardless of this bug.
- Set expectations that a fix timeline hasn't been announced - avoid promising a specific recovery date.
Separating this from the AI Overviews CTR trend
Agencies should be careful not to conflate this with the broader, well-established drop in organic CTR on queries where AI Overviews appear - that's a structural, long-term shift Google has no plans to reverse. This bug is narrower and Google has explicitly called it unintended behavior in a specific model release, which makes the appropriate response completely different: wait for a fix rather than adjust content strategy.
A monitoring approach for the coming weeks
Rather than a one-off check, set a recurring cadence: pick a handful of queries per client account that reliably produced citations before September 2026, and re-check them every few days on a Pro/Ultra account. Track whether recovery happens gradually across query types or all at once - that pattern will tell you whether Google is rolling out a partial patch or a full model fix.
If citations remain absent well into late September 2026, submitting a specific reproducible example through Search Console feedback tends to carry more weight than a general complaint, based on how Google's product teams have handled similar confirmed bugs in the past.
FAQ
Should agencies pause GEO reporting for affected clients? No - continue reporting, but flag this specific bug as context for any citation drop observed in early September 2026, rather than attributing it to content quality.
Does this affect all AI Mode users? No, only Google AI Pro and Ultra subscribers - free-tier AI Mode uses a different model that isn't affected.
Is there an official timeline for the fix? No. Robby Stein confirmed the bug on September 4, 2026, without giving a specific date for resolution.
How is this different from the AI Overviews CTR decline? The CTR decline is a long-term structural trend in how AI Overviews affect organic clicks. This is a specific, temporary, Google-acknowledged bug tied to one model release.
What's the best way to verify a client is actually affected? Manually run the client's key tracked queries on a Google AI Pro or Ultra account and compare citation presence against historical GEO tracking data from before September 2026.
For long-term GEO strategy guidance, see our Generative Engine Optimization guide and the underlying data on the AI Overviews CTR drop.
