Ctrl+F cannot find a word you can see. Here is the fix.
You can see the word on the page, but Ctrl+F or Word search says it is not there. The cause is almost always an invisible character sitting inside the word, splitting it into two tokens for every tool that reads raw characters. The fix: paste the text through the cleaner on the homepage, copy the clean version back, and search again. The word matches now, because the string is finally what it appears to be.
How to confirm this is your problem
Copy the failing word and paste it into a character inspector or the cleaner box. A zero-width space (U+200B) or a similar hidden character shows up as a flagged position with no visible glyph. Alternatively, delete the word and retype it by hand, then search again: if the retyped copy matches and the original did not, the original carried something invisible. Non-breaking spaces cause the same symptom between words: a phrase search fails because one space is U+00A0 instead of U+0020. All of these render identically and compare differently, which is why looking harder never helps.
Why Word and Docs are hit hardest
Word documents accumulate invisible characters over years of edits, tracked changes and copy-paste from the web. PDF exports add their own layout characters, then web uploads of those PDFs add more. Google Docs inherits whatever the browser clipboard carried, including zero-width spaces from chat tools. The result is a document where some paragraphs search fine and others silently do not, with no visible difference between them. Cleaning the pasted text before it enters the document prevents the next occurrence; cleaning the export fixes the current one.
Cleaning a whole document
For a few paragraphs, the on-page cleaner is the whole workflow: paste, copy the clean version, replace the original. For a full report or manuscript, work section by section so you can diff each replacement before committing. Keep one original copy until search and spell-check pass on the cleaned version. Code samples and preformatted blocks wrapped in backticks pass through unchanged on this site. For the deeper explanation of which characters split words and why a blanket strip would be wrong, read why your search box cannot find a word you can clearly see and how to remove zero-width spaces.