Does this PBKDF2-SHA1 payload hint at a cryptographic security issue?
So lets take a look at this in hex:

626B3A C6AAF309F16C41A755679810A2732D9D 00000000000000000000000000000000 10270000 EBDB5836


This is bk: in ASCII, then 16 bytes of ciphertext, followed by an all zero IV, then a iteration count in hexadecimals : 10,000 (0x2710 in little endian), followed by what I presume is a 4 byte checksum or key check value.

So from a cryptographic standpoint this looks correct, unless an all zero IV is not acceptable.

Notes:


You cannot just start with character A when reading the IV. Byte boundaries for base 64 are within the characters for 3 out of 4 boundaries (or 5 if you count the one for the next byte). So you should always first convert the base 64 to hex.
Instead of 16 bytes of ciphertext I would expect 16 bytes of salt, used for the key derivation function. If those are random then it is alright to use an all zero IV, as the key would be different even if the same password is used; the random salt would make sure of that.