MTR 4 still have some issues / regressions introduced since MTR 3, which you can help the development of MTR 4 by contributing to such area.

• Train will not render with Sodium in MC 1.19.4 (Or Rubidium on MC Forge 1.20.1, switch to Embeddium in that case)
• F3+T/lagging when riding a train will kick the player with Invalid move player packet received (Can repo in Singleplayer)
• Built-in R-train is lacking some interior decoration
• Sometimes certain train will be completely silent, then become normal again after riding the train for a period of time
• OBJ Model loading is slower than NTE (Partially addressed in JCM v2.2)
• When path refresh failed, it may say “Failed to generate path for n sidings”, where n may be larger than the amount of sidings in the depot. (In path generation, path for both OUT depot (To main route) and IN depot (Return to depot) direction are searched. If it is exactly 2x the amount of sidings, it means both path segment failed. If it is normal, then either the OUT and IN depot segments have failed.)

• Exception/Crash when loading rail model which points to an non-existent file

• Train announcement still gets played even when in-game sound volume is 0
• Occlusion culling might be slow, causing trains & tracks to take a longer amount of time to show up (Resulting in train/tracks suddenly appearing out of nowhere, decreasing render distance helps)
• BVE sound would get stuck if the train got occlusion culled
• Rail model may occasionally flicker with a dimmed color.
• Some mod combinations would result in vehicles getting speed up with shaders enabled

• Ding Sounds in Elevator
• Scripting functionalities from Nemo Transit Expansion (NTE) mod (Similar functionality provided by JCM v2.2)