@esc0rtd3w tested version v004-TEST-VERSION-1 4.81 DEX, after a successful initialization and clicking on the Execute Chain freezes on previous versions as well.
You are testing in DEX so have you tried using the ProDG debugger to find out where the problem might be?
esc0rtd3w already explained how to make vsh attachable & debug the ROP chain.
You would typically start with a breakpoint on chain start ie 0x976bc in DEX 4.81.
From there you can step in & see the parameters being loaded before each syscall or export. Parameters are usually loaded by the gadget starting at 0x6161b8 on DEX.
As explained in the tut, parameters of an export or syscall are passed in registers r3 to r11 & in that order ie 1st param = r3, 2nd param = r4 etc...
In the specific case of a syscall however, r11 is not the 8th parameter but the syscall number.
When a syscall or export fails, it returns an error number placed in r3 in the standard way ie 0x8xxxxxxx.
At the last instruction (usually blr) of an export or syscall gadget, if the value in r3 is 0xFFFFFFFF8xxxxxxx it means an error occurred. If the error is unexpected & it is always the case in the tutorial ROP chains, most of the time it is because of 1 or more bad parameter(s).
Refer to psdevwiki:
Error Codes listing for error identification.
http://www.psdevwiki.com/ps3/Error_Codes
Syscalls list
http://www.psdevwiki.com/ps3/LV2_Functions_and_Syscalls
VSH exports list
http://www.psdevwiki.com/ps3/VSH_Exports
Using the debugger is the only way to understand what's going on & basically learn anything at all in this tutorial.