@Chetan Ninghot,
The problem was not with Singular/Plural. It was with the case sensitivity. I have made a small correction to address that.
Please find the corrections below:
1) Added a stage to convert input to Upper case.

2) Changed the terms like day, hour etc in Choice stage to upper case.

3) Changed the terms in all multi calc stages to Upper case. Providing screenshot of multi calc stage for Day in Choice stage below:

Just like this, change the Hour, Minute, and Second to all upper case -> HOUR, MINUTE, SECOND.
This will resolve the issue. Please check next comment for the correct output of the inputs you have mentioned.
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Arun K J
Consultant - Automation Developer
WonderBotz India Pvt. Ltd.
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