While investigating CQLIT-506 re potential new logic for QDM CMS646, a potential issue was detected with RelatedTo QDM attribute entry and storage in MADiE compared to MAT.

Testing cloned proposed logic in TestCQLIT506BCG using return Tuple "DISPLAY ONLY" technique did disclose additional insights that have impact on your issue.
MADiE TestCase1 images for StagingProcedure and BladderCaDx from 20250214 are attached.  After entering and saving as a new test case in the modified test measure, the Staging Procedure relatedTo attribute is displayed as '67ad172c04b7ec26296ef256 - Diagnosis: Bladder Cancer for Urology Care'.
Note that 67ad172c04b7ec26296ef256 represents a hexadecimal GUID which further complicate GUID to string comparisons.
Testcase1 return tuple for "DISPLAY ONLY Bladder Cancer Staging Procedure" illustrates challenges of aligning BladderCADxId to StagingRelatedTo:
[

{   BladderCaDxAuthorDT: 04/06/2026 8:01 AM,   BladderCaDxId: "67ad172c04b7ec26296ef256",   StagingProcBodySite: CODE: SNOMEDCT 89837001,   StagingProcBodySiteBladder: true,   StagingProcId: "67ad157504b7ec26296ef253",   StagingProcTiming: 04/05/2026 8:00 AM,   StagingRelatedTo: ["67ad172c04b7ec26296ef256 - Diagnosis: Bladder Cancer for Urology Care"],   StagingRelationshipEq: null,   StagingRelationshipEqv: null,   StagingRelationshipIn: null,   StagingRelationshipStartsWith: null }

] 
Checking other measures (e.g.129) using relatedTo and saved early last year revealed that Procedure is displayed as Related To - 5c6af32eb848460b42f81042.
This raises the question of test case relatedTo attribute storage in MADiE vs MAT. This could impact other measures and Measure Developers currently using the relatedTo attribute in QDM; therefore, a MADiE ticket will be created with you flagged as a watcher for 646 and AIR for 129.
Since you have flagged resolution as confirmed due to deferral, will flag this CQLIT ticket as resolved with  a new ticket entered on MADiE.
Thank you, PMuir MD  eCQM Standards Team

Please add bkent@air.org as Watcher.