Hi mikoyan99,
one fact, that this aircraft was not in operational service was the difficult handling and the lack of technical reliability.
The first 8 Bv 141 were the BMW 132 powered A-Versions who had, for example ,many different lengh sizes of the "stabilizer fuselage"
The reason for that were many test flights to solve the dynamic stability in flight modus.
In 1939, B&V and the RLM decided to launch the Bv 141B development with the stronger BMW 801 engine and a greater wing span and fuselage length. Before this B-Version started to his first test flight in January 1941, the planned production series of more than 100 Bv 141A and 161 Bv 141B were stopped from the RLM in March 1940. The reason for this decision from the RLM was the more successful Fw 189 with two cheaper Argus Engines, which were easier to produce.
The RLM and B&V decided after the stop of an production series to produce 18 Bv 141B, which were tested in different tasks. B&V had in 1940 the hope to bring the Bv 141B in service and be able to assure the RLM with good results of the Bv 141B flight tests.
But even the Bv 141B had many technical problems, which cant be solved during the test period.
In 1941, a test squadron of Bv 141B were planned from the RLM, but never went in service because of the lack of spare parts and the lack of priority on this aircraft. So all Bv 141 were used at schools, as test beds for engines and weapons and some more other tasks.
I hope, this little information answers most of your questions!
Best regards,
starmountain