ConvertToLocalTime returns different results after moving from QV11 to QV12.xx release track

ConvertToLocalTime returns different results after moving from QV11 to QV12.xx release track. Please see the example below:

What is supposed to be done?
Convert a timestamp to date.
What is the expected result?
Two selected rows should return 1/Nov/2018 and 12/Apr/2019
What is the actual result?
Two selected rows return 1/Nov/2018 and 13/Apr/2019 Dates in summer time (Apr-Oct) return a different day. Dates in winter time return correct date.

The ICU library does indeed support GMT+01:00, but not in combination with DST. This is due to the fact that GMT is a longitudinal (east-west) offset, whereas DST is a latitudinal (north-south) offset. In other words; both Helsinki (Finland) and South Africa share a similar GMT offset (i.e. GMT+02:00), but they do not share the same DST offset (i.e. Helsinki is located in the northern hemisphere while South Africa is located in the southern hemisphere). This means that any DST offset requires info about the latitudinal position of the local time zone (i.e. geographical time zone input) and not just the GMT offset, in order to have full information about local DST conditions.

1. Remove the 'GMT+01:00' parameter from the expressions. Works both in QV 11.20 and 12.20. 12.3 and 12.4

2. It seems that results in the example above are correct since from the QV November 2018 version we have removed some time zones to better match the standards. Thus if you want to keep you your time zone you need to provide the time zone or a geographic location.

3. Please also see the article titled: New ICU standard causing a change of behavior in functions "ConvertToLocalTime" and "LocalTime" . The article explains changes between the versions.