In order to resolve this synthetic key, we'd need to understand your data model and the meaning of all tables and fields. If you'd like to explain it in detail, we could offer some advice.
Thanks for your question and welcome to the Qlik Community. In order to reduce any misinformation, can you expand on what you mean by "not showing relevant data" - a synthetic key for the most part is harmless and technically should not effect the results of the data. It is not an optimal data model, but should not cause any data errors, so I am curious. The post provided by our members above is a great primer: Synthetic Keys.
A synthetic key is how Qlik resolves an association between tables with multiple columns that have the same name. (composite keys) The resolution for this is to usually rename those columns or qualify them with the table name, that way they don't assocaite. You can also try using the Data Profile feature (Smart Data Load) available in Qlik Sense 2.0 - this may help resolve some of these for you and recommend an approach.
Let us know how you do, we are here to help and make you successful.
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