Expiration date for option contract is 12/18/20, but "expir_date" is showing 12/17/20. I didn't have this issue with Thomson Add In, only with Refinitiv. Thanks!
The Helpdesk investigation determined the issue is a bug related to 'Adjust to system timezone' Data Retrieval Setting in Eikon Excel. The bug will be fixed in future releases of Eikon. In the meantime the workaround is to untick 'Adjust to system timezone' checkbox in Eikon Excel Settings - Data Retrieval Settings.
Which options are you looking at? It would be helpful if you could specify the RIC. I'm for example looking at IBML182012500.U and I see the value of 18DEC20 in EXPIR_DATE field. For future reference if you suspect any data you retrieve to be incorrect, please report the issue to Refinitiv Helpdesk, which you can reach using Contact Us capability in your Eikon application (from the main Eikon menu select Help - Contact Us) or by visiting MyRefinitiv.
For the following, I see 12/17/20 for EXPIR_DATE.IBML182012500.U
Where exactly do you see 12/17/20? Does =TR("IBML182012500.U","EXPIR_DATE") return 12/17/20 for you? What if you type in IBML182012500.U in a Quote app in Eikon application? Do you see 17DEC20 against Exp. Date label?
I opened case 09412303 with Refinitiv Helpdesk for the problem you experienced. You will be contacted by Refinitiv Support to investigate the issue.