Form Date Time not working in Sheets (Zoho Form with Zoho Sheets Integration)

hi,

I've been using the 'Added Time' from a Form to Sheets since April. It worked perfectly, but for some reason since 20 December Sheets will no longer recognise the 'Added Time' as a Date Time cell. The cell format is correct, and the Form & Sheets date/time/region are set as UK GMT. Please advise how to correct this issue and the reason it suddenly started?

Please see in column A the Added Time is OK for the first row, the date/time is in the right of the column and in column B I am able to do a simple date calculation.
(I have hidden many rows between 22 Apr > 20 Dec and the date time worked fine for them.)
For the next row which has date stamp starting 20-Dec, the field aligns left in the column and in column B it will not do a simple date calculation.

The cell format in column A is the same. Please see cell format of A2 below:

The cell format for 20 Dec has the same setting, but note the Preview shows the current date/time as it doesn't recognise the field as a Date Time field.

I have tried many different date/time settings but none of them correct the date time, which remains from 20 Dec on the left of the column.

Since the form settings appear to be correct I'm not sure what to try - please advise?

Thank you

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