What I am saying is, is if -reindex is specified at all, Actiniumd will crash at the same block height posted above. txindex does not matter, on or off it will crash. Sometimes I can get an initial sync to work with it but usually it will crash. After initial sync, any future run of the software even without -reindex (as should normally be done) will crash.
I have tried initial sync with -reindex -txindex, only running -txindex later, it eventually crashes / quits shortly after launch just like before.
On any of my machines, macOS/Win/Linux, the sync runs without any errors. Actually, it already ran with the normal verison 0.17.4.0, but it's also syncing with the "special edition".
I really don't know what could be the next option to try. I have released the binaries for macOS & Windows in the posting above, so I will wait for user reports before trying anything else as it's simply too dangerous to change the code without more data from different users.
Sorry that I can't help you find a solution but for now I have no other option to try.
--EDIT--
I will now push another variant that is more tolerant towards those few problematic transactions. Another user (windows box) reported a similar issue. However, I didn't get the info on what block, so we will have to test it step-by-step. But I have checked the code and comments from Bitcoin team and according to them, a block could also have Witness Data appended even if there was no SegWit activated. A bit of background info here: We didn't activate SegWit by default, but had a normal voting period. I could have put SegWit to active from the beginning, but I wanted to make it "clean". However, some mining pool operators mistakenly activated the SegWit-option in their mining software (like YIIMP) which of course has nothing to do with our Wallet/daemon or even voting period. And because Witness Data could also be appended when there is no SegWit active, such blocks would look problematic to the wallets. Some time ago I have already informed certain miners to deactivate the settings, if they're running the old Actinium versions, or to update them. However, there are a few blocks which are valid, but also contain "too much" data so to speak. Therefore I will now create a new variant that accepts those redundant data from the past.
--EDIT 2--
The fix is now available on GitHub, same branch. Please, test if you have time (I hope you didn't run away *lol*) and let me know if it works on your side. Many thanks!