**Our Take: When Network Access Works but Power Query Doesn't**
This user's problem is maddeningly specific and entirely relatable. A Power Query connection that worked for months suddenly fails, while the exact same network path remains fully accessible through File Explorer. The folder is there. The CSV files open without issue. Nothing changed on the user's end. And yet, the query refuses to connect. Our opinion is plain: this is not a user error, and it is almost certainly an IT-side configuration change that broke something silently. The user's suspicion about sensitivity labels is worth taking seriously, because Microsoft's sensitivity label infrastructure can interfere with Power Query's ability to authenticate to network sources, even when those sources previously required no credentials.
The practical takeaway for anyone working with Power Query in a corporate environment is that you must treat your data source as a system dependency, not a static file path. When a connection breaks without any change to the file or the folder, the culprit is almost always an update pushed by IT: a group policy change, a new security patch, a shift in how network drives are mapped, or, as the user correctly noted, sensitivity labels applied at the tenant level. These labels can block Power Query's anonymous credential model because the query engine now sees the folder as a protected resource, even though the user can still browse it manually. The user's attempt to remap the drive letter and update the path is a logical troubleshooting step, but it won't fix a permissions issue that lives above the file system layer.
What this means in practical terms is that rebuilding the query from scratch is unlikely to help. The problem isn't in the query definition; it's in the environment the query runs inside. The fix requires engaging IT to check for recent policy changes, particularly around sensitivity labels, network drive permissions under the Power Query engine's security context, and any conditional access policies that may now apply to the folder path. The user should also test the same query with a local copy of the CSV files to isolate whether the issue is network-specific. If the local refresh works, the problem is confirmed as an infrastructure-level block, not a query design flaw.
The lesson here is that Power Query's reliability depends on more than correct paths and credentials. It depends on the entire chain of authentication, authorization, and network routing that sits between Excel and the source files. When that chain changes, and in a managed corporate environment, it will, the query breaks first, and the user finds out last. Our advice is to stop troubleshooting the query and start asking IT what changed. That's where the real answer lives.