Can not get daycount right

I have a strange issue with the calculated number of days.

Today it’s October 5, 2019 and I use the following shortcode:
echo do_shortcode('[tminus t="2019-10-27 23:59:59" /]')

Page source shows me the following, which seems correct:

targetDate: {
	'day': 	28,
	'month': 10,
	'year': 2019,
	'hour': 00,
	'min': 	59,
	'sec': 	59,
	'localtime': '10/5/2019 11:18:15'
},

This should be some 22 days form now, but the counter is showing
“01” day.

If I change the date to for example:
tminus t="2019-10-10 23:59:59"
the counter shows 05 days, which is correct

If I change the date to for example:
tminus t="2019-10-20 23:59:59"
the counter shows 01 days, which is incorrect

I’ve also tried the following:
tminus t="10/27/2019 23:59:59"
tminus t="October 27, 2019"

I deactivated the Autoptimize caching plugin, it made no difference.

Can you please help me try to understand what’s going on?
Any help would be really appreciated.