Error: Condition column <column name> of Lookup <transformation name> (with existing cache) was not found in Lookup <transformation name> (that is trying to find one to share) even though they have the same cache file name prefix <cache file name>.
When you have multiple Lookup transformations in a mapping, the first lookup creates a cache file. The second lookup tries to use the same cache file, but cannot because the condition does not match. Because both lookups use the same cache file name, the second lookup cannot create a cache file.
If you do not want to share the cache, change the cache file name for one of the lookups. If you want to share the cache, make sure the shared transformations use the same ports in the lookup conditions.