It should get mined eventually. Background. Some mining pools use a configuration option to limit the number of inputs they are willing to mine e.g. Flypool is around 150 but some others accept 500. The reason for this is that as the number of inputs rises, so does the time to prepare a block for mining, which might impact their chances of winning the race to mine a block. This “quadratic hashing” issue has been resolved in the upcoming network upgrade, Overwinter, scheduled for June/July. At that point the configuration option will be deprecated and mining pools will stop using it so transactions with hundreds of inputs will be mined promptly.