Armorstand issue DisabledSlots . offhand does not work

We have the following table for the Armorstand NTB  - DisabledSlots

2^0 1 Disable adding or changing mainhand item
2^0 1 Disable adding or changing mainhand item
2^1 2 Disable adding or changing boots item
2^2 4 Disable adding or changing leggings item
2^3 8 Disable adding or changing chestplate item
2^4 16 Disable adding or changing helmet item
2^5 32 Disable adding or changing offhand item
2^8 256 Disable removing or changing mainhand item
2^9 512 Disable removing or changing boots item
2^10 1024 Disable removing or changing leggings item
2^11 2048 Disable removing or changing chestplate item
2^12 4096 Disable removing or changing helmet item
2^13 8192 Disable removing or changing offhand item
2^16 65536 Disable adding mainhand item
2^17 131072 Disable adding boots item
2^18 262144 Disable adding leggings item
2^19 524288 Disable adding chestplate item
2^20 1048576 Disable adding helmet item
2^21 2097152 Disable adding offhand item

This would give us an alltogether of  4144959 what mean all places are block

now if you give the armorstand an item into the main hand when creating it + disabed all slots

Then we aspect we cant give it any items

but we still can equip the Offhand once.... what was not wanted in that case..

So i assume this is a bug that still exists.