WiredTiger runs upgrade downgrade compatibility testing, it has two variants of this: "Compatibility tests" and "Compatibility tests full", the first was made to run more frequently with a small range of versions, it was also made shorter to reduce the number of artifacts uploaded at the end.
Currently the "Compatibility tests full" variant doesn't complete uploading artifacts at the end as evergreen implements a global 15 minute timeout for artifact upload. This can be seen on any run, e.g.: https://evergreen.mongodb.com/task/wiredtiger_compatibility_tests_full_compatibility_test_for_releases_full_c97151853eb2e8f66e14c9671e120ba755675dba_20_07_09_22_23_24
At the time of the creation of this ticket investigation was performed to see if the deadline implemented by evergreen could be increased, and the response from the evergreen team was that it can't be. Hence the compatibility test script needs to be improved to reduce the amount of artifacts it tries to upload, which may also include modifying the default wiredtiger artifact selection in our evergreen.yml.