A form of this has already been reported but I want to clarify to help you be able to fix it.
As already stated in the new 1.5 update, Auto attack is overzealous.
If you're near anything that you would be able to attack, even the bugs in skull cavern that you can't kill, it won't let you off of Auto attack.
It's made getting to level 100 of skull cavern obscenely difficult.
You need to be able to heal and you can't....
Now, since I've set the scene, here's the helpful part:
If you used auto attack in the old mobile version, it would still let you toggle and use other items.
You just wouldn't attack while those items were selected...
This includes food, bombs, etc.
Additionally once you use a bomb it knew not to keep bombs selected. That way you don't accidentally use multiple.
You would have to reengage Auto attack by selecting your sword.
So that's the reminders from 1.4.
As previously stated unless you select scythe as your weapon you can't use scythe in the mines or skull cavern ... Once selected you can only use it as a weapon. It won't let you use it to cut weeds or open boxes in the mines.
So I really hope this is helpful, but after 46 consecutive failed attempts at skull cavern invasion, the most recent one because of dying because I couldn't eat any food when I was on level 91, I felt compelled to write more here.... **** SIGH ****
I agree with this poster, especially when trying to kill the mummies - my least favorite enemy - in Skull Cavern. I used to be able to get them into the “downed” stage (using my sword), select a bomb, and detonate it. In 1.5 after selecting a bomb, it takes me right back to my sword which I’m swinging aimlessly at already downed mummies. By the time I can get a bomb off, they’re already reviving. I found that after initially downing the mummies if I stepped back a bit, I could get a bomb off…unless there was something else around that would activate my sword. I can also no longer run past mummies (especially in the narrow hallways) by un-selecting my sword because it gets auto-selected.
The inability to override auto-attack affected me in the volcano also. There was a slime and a Hot Head on the other side of a couple of rocks; I was hemmed in (huge lava pool on one side, a wall on the other), and there were no other rocks to move to. When I tried to choose my pickaxe, I immediately went back to swinging my sword. My only workaround was to step back and use a bomb to get rid of the two rocks. (This happened before 1.5, but there were usually other rocks around I could move to.)
There are times when the new auto-attack comes in handy though. For instance, it’s so much nicer now after running into a cluster of rocks to set off a bomb then running away getting chased by serpents and bats, that I no longer have to manually choose the sword before they catch up to me.
One of my greatest “finds” lets me no longer have to worry about the dreaded mummies in Skull Cavern. I lucked out when forging my sword, and randomly got the Crusader enchantment. When I looked it up, I found that it prevents mummies from reviving - and it works!
No need to bomb them anymore, and I still get their goodies! I’m so happy!🥲
Thank you again, Eric, for such a great game, and for not bailing on us mobile players.
There are so many new things to discover and try! It was well worth the wait!
OP, I mostly used stairs to beat that quest. I only tried the “honest” way once, but too many things - monsters, bombs, using holes - affected my health, so I crafted a bunch of staircases and traded in jade for some more at the Desert Trader. You don’t get dinged using stairs in this quest.
There are also some new rings that help with health that you might want to look into, but, obviously, you’d have to have them to be able to use them. Look into forging rings too, if you haven’t already. I forged the Slime Charmer with the Crabshell, and am very happy with the results. I’m waiting for the Lucky Ring to forge with my Iridium Band.
I miss playing SV. I have read that there are people here who have the same error on the same series of phones: Samsung S10 S10e and S10+ 
