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FSI Solid-Side Multiple Time Step Not Executed, Causing Fluid-Side TCP Error

Hello everyone, I am conducting a SimLab FSI (Fluid-Structure Interaction) analysis and encountered a problem. I would like to seek advice from experienced users.
1. Problem Description
The solid side (OptiStruct) was set with multiple time steps, but in practice it does not execute exactly as specified.
The fluid side (AcuSolve) ideally should follow the same multiple time steps and is currently executing correctly.
The solid computation progresses too fast:Solid side completes at t = 1 sFluid side has only reached t = 0.55 s
The time steps are not synchronized, preventing proper data exchange between the two sides.
Additional Note (Theoretical Perspective)
In theory, FSI requires the solid and fluid sides to synchronize their time steps for correct coupling.
Currently:The solid side does not follow the specified multiple time stepsThe fluid side executes correctly
Therefore, even though the fluid results are generated successfully, the overall FSI solution is not reliable due to the unsynchronized solid side.

2. Multiple Time Step Settings (Intended)
| Time Range (s) | Time Step (s) |
|----------------|---------------|
| 0 – 0.5 | 0.01 |
| 0.5 – 1.0 | 0.001 |
Total Time: 1 s
Explanation: Intended to use 0.01 s for the first half and 0.001 s for the second half
Goal: Both solid and fluid sides follow these multiple time steps

3. Observed Behavior and Error Messages
When the fluid side attempts to exchange data with the solid side, the following error occurs:
acuSolve: *** ASSERTION in Function <iopWriteSock> File <iopSocket.c> Line <612>acuSolve: *** TCP socket write error; Permission deniedacuRun: *** ERROR: error occurred executing acuSolve
FSI coupling is interrupted
The solid side appears to complete, but the coupled solution is not reliable

4. Attached Files / Screenshots
For convenience, I have also attached the OptiStruct and AcuSolve HM files, .fem and .log files, as well as cci.txt and .out files.

Question for the Community: In FSI analysis, if the solid side cannot follow the specified multiple time steps and becomes unsynchronized with the fluid side, causing TCP errors, has anyone experienced a similar issue? Which settings are most likely causing this behavior?