Most problems fall into one of a few categories, and several things that look like faults are the extension telling you the truth about missing data. Start here.
Work through these in order.
-Citation Bar On-. Click it to switch it
back on, then reload the page.
The extension leaves a gap visible rather than filling it with a plausible-looking substitute. Here is what each gap means.
| What you see | What it means |
|---|---|
| RCR - | iCite is slow or unavailable. Citation counts fall back to Europe PMC, but RCR is an iCite-only measure, so no substitute is shown. Usually resolves on its own. |
| IC - | Semantic Scholar has no record for this article, which is common for very recent papers. |
| Alt greyed out | The article has no DOI, so there is nothing to look up at Altmetric. A greyed Alt is not the same as an Altmetric score of zero. |
| doi greyed out | No DOI on the PubMed record. About 3% of articles. |
| Author metrics blank | No ORCID on the record. Author metrics come from OpenAlex keyed by ORCID; matching by name would return the wrong researcher, so nothing is shown. |
| MeSH empty | The article isn't MEDLINE-indexed, so it has no MeSH terms yet. It may get them later. |
| SJR - | The journal's ISSN isn't in the SCImago table. |
m
flag does not always mean the article will never be indexed. A growing
number of records sit in an "in-process" state for extended periods, so
filtering a search by MEDLINE can quietly exclude papers that are simply
waiting. The PubMed Summary
report tracks this year by year if you want to see the scale of it.
| Message or limit | Explanation |
|---|---|
| Scan 1,000 | Walks up to five pages of 200 results — 1,000 articles — in about a minute. |
| "Scan 1,000 only works on PubMed search, trending, or collection pages" | You're on an individual article page or somewhere unsupported. Run a search first. |
| "High Impact filter only works on PubMed pages" | Same cause. |
| "No High Impact items found" | Nothing on the page clears your threshold. Lower it in the popup — the default is 5, and it adjusts from 1 to 6. |
| "Limited to first 20 terms" | Term Analysis takes a maximum of 20 terms. The first 20 are processed. |
| Special mode | Up to 10 term groups separated by blank lines. Line 1 must be Special:, line 2 a period in the form Last X days/months/years, with X between 1 and 100. |
| DOI collection | Up to 15 DOIs can be gathered and viewed together in DOI Lookup. |
| "Failed to search external databases" | OpenAlex or ClinicalTrials.gov didn't respond. Usually temporary. |
Try these first, in order — they fix nearly everything and cost you nothing:
Only reach for Reset Extension if the extension is genuinely stuck after all of that, and you're willing to lose your browsing history and active sign-ins.
A report is far easier to act on with these attached. Both are in the extension popup.
Also helpful: the exact PubMed search you ran, and what you expected instead.
Questions, bug reports and suggestions all go through the Chrome Web Store support tab. It reaches me directly and keeps everything in one place.
Suggestions for the curated top-journal list are welcome. It's deliberately small and selective, but it isn't fixed.
Short walkthroughs — screening a search with High Impact and Scan 1,000, building a clean query with Xout, and using Term Analysis to test which phrasing actually finds the literature — are planned for this page.
Until then the reference page covers every element on the bar, and NLM's own PubMed training is a solid grounding in PubMed itself.