Bitemporal tables - application time not working correctly

Hello,

i tried to use the bitemporal table feature but it is not completely working correct i think.
I've created a little example to show you what i am talking about.

First my create table statement on which i want to use the bitemporal feature:

CREATE TABLE pricelist

(

    id            int(11) NOT NULL AUTO_INCREMENT,

    price         INT(11),

    valid_from    DATE,

    valid_to      DATE,

    row_start     TIMESTAMP(6) AS ROW START,

    row_end       TIMESTAMP(6) AS ROW END,

    PERIOD FOR application_time(valid_from, valid_to),

    PERIOD FOR system_time(row_start, row_end),

    PRIMARY KEY (id)

)

WITH SYSTEM VERSIONING;

Next i inserted one row where a price of 100 is valid from 2020-01-01 to 9999-12-31 (valid to an infinite period):

INSERT INTO pricelist (price, valid_from, valid_to) VALUES (100, '2020-01-01', '9999-12-31');

Now i want to update this dataset with the "FOR PROTION OF" statement to set the price to 150 valid from 2019-01-01 to 9999-12-31 (infinite):

UPDATE pricelist FOR PORTION OF application_time FROM '2019-01-01' TO '9999-12-31' SET price = 150 WHERE id = 1;

I've expected the result after the update to be one record with a price of 150 valid from 2019-01-01 to 9999-12-31 because it overrides the existing dataset because it overlaps the initial time period. But this is the result i get:

Something similar happens when i want to update the initial dataset to a price of 150 valid from 2019-01-01 to 2020-06-01 with this statement:

UPDATE pricelist FOR PORTION OF application_time FROM '2019-01-01' TO '2020-06-01' SET price = 150 WHERE id = 1;

The second row i expected to be created is created correctly. But the first row (id = 1) again is not updated correctly i think. I expected the valid from date to be 2019-01-01 but it is 2020-01-01. Here the full result after the update:

So is this a bug or am i missing something? And when i am missing something....how to update the dataset to change the valid from date to 2019-01-01 in the correct way? Or have i to do this by myself?

Greetings
Niklas