I used to work with Blockfrost API to submit my transactions. A few days ago, I ran into this problem in which my transactions were submitted successfully (The API returned me the transaction id without any error) but the transactions were never actually processed (When I looked for transactions in the Cardanoscan, nothing was found). I decided to submit my transactions on another node, and it did work fine for a couple of days, and now I have the same issue. Does anyone know where the problem might be?
The chain has been pretty congested since sundaeswap launched. It may take some time between transaction submission and inclusion into a block. If your TTL or --invalid-hereafter parameter is too short, the TX may be submitted to the mempool but be invalid by the time it is to be included in a block. Try setting the TTL to something like 10000+ and see if that helps.