NUMBERS pretending to be NULL in Oracle Cloud Database

Our Delphi Application uses the 19.18.0.0.0 Oracle client to connect to a Oracle 19c Database in the Oracle Cloud.

Since a few months whenever it inserts some special numbers into number colums the field looks like NULL to all other applications.

Selected by the application itself the number appears to be correct.

The fun begins when you do something like this with Oracle SQL Developer or any other application:

-- Creating test table

CREATE TABLE TEST (

   TOOL NUMBER(1),

   COL1 NUMBER(15,2)

);

-- INSERTS performed by the application

INSERT INTO TEST (TOOL, COL1) VALUES (1, 196);

INSERT INTO TEST (TOOL, COL1) VALUES (1, 197);

INSERT INTO TEST (TOOL, COL1) VALUES (1, 198);