I found the problem and the solution.
- Problem: I couldn’t send MIDI to my Strymon El Capistan v2 and Cloudburst pedals using normal cables.
- Solution: Use MIDI EXP cables.
Strymon support said, “Our pedals require a component called an opto-isolator to be present on any DIN -> TRS cable, in addition to having the cable made to send MIDI on the TIP of the TRS connection, and receive on the RING. TRS MIDI Type-A is the most common type of cable out there, which works differently than this, and can cause issues from time to time. This is why we only recommend our MIDI EXP cables, as those meet all of our specifications and will work well.”
When I ordered MIDI EXP cables, the MIDI signals started working as desired.