RE: How to display text of the lookup field on the data table in PowerApps for dynamics 365?
All, I know this answer comes a bit late.... but I had the same exact problem and wanted to shared how I went about resolving it.
In my case, the lookup was not into accounts, but into another custom entity that represented a collection of Assets. I needed to display in my data table the asset serial number, but also some other attributes in addition to the serial.
My data table is displaying a series of records than the end user is collecting via the PowerApp. These records are being captured in a CRM entity called 'EventRecords'
My EventRecords entity obviously has my lookup to my ASSETS entity and inside CRM it displays the actual serial number of the Asset.
If I selected the Lookup 'Serial' field in my datatable connected to 'EventRecords' I get the GUID display (like your accounts above)
What I did is I created a calculated field in the EventRecords entity I called 'Serial_Label' of type SINGLE LINE (text) and I defined it as: =ASSETS.serial_number (which contains the actual textual form of the serial)
Then I published and refreshed all schemas and voila, now in my datatable I can select the field 'Serial_Label' that effectively displays the serial number of the related asset instead of the GUID.
You can apply the same technique for other attributes of the lookup entity.
Hope this helps