Just like Duel Links there is a couple of skills in Speed Duels that are bugged.
Cocoon of Ultra Evolution
The 2nd effect of the skill to shuffle 1 insect in the GY to your Deck produces this Internal Error and forces the duel to end.
Nightmare Sonic Blast!
The skill simply just does not work. You meet the requirement of having Serpent on the field and flip the skill but you can’t activate the skills effect.
Spell Proof Armor
It doesn’t allow you to normal summon a vanilla monster that only needs 1 tribute. The skill should remove that 1 tribute cost but it does not happen.
The Skill is not properly working, while it does Fusion Summon a monster using materials from the GY or Field. Fusion Monsters like the XYZ Dragon Cannon have to banish the materials, the skill bypasses this restriction and only sends to GY. In addition the skill is not once per turn as it says in the text. So since it does not banish, we can simply just activate the skill over and over again and keep fusing into XYZ and its counter parts with no restrictions holding them back.
The activation of the skill indicates that it needs to be flip over when the Duel begins. “Skill activation: At the start of the Duel, flip this card over.” Omega does not do this. The 2nd effect to remove 3 counters to destroy 1 face-up card is not selectable, it only does the 1st effect to discard 1 card from the hand. Forgot the screenshot for this one.
Related Screenshots of the Bugs in-game are shown here: Speed Duels Bugs - Album on Imgur