Some actions hang forever

Executing some actions never returns a response:

curl -u "admin:<pass>" -k https://52.177.21.26:3535/api/v1/actions/rbuilder_restart -v
*   Trying 52.177.21.26:3535...
* Connected to 52.177.21.26 (52.177.21.26) port 3535 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
* TLSv1.0 (OUT), TLS header, Certificate Status (22):
* TLSv1.3 (OUT), TLS handshake, Client hello (1):
* TLSv1.2 (IN), TLS header, Certificate Status (22):
* TLSv1.3 (IN), TLS handshake, Server hello (2):
* TLSv1.2 (IN), TLS header, Finished (20):
* TLSv1.2 (IN), TLS header, Supplemental data (23):
* TLSv1.3 (IN), TLS handshake, Encrypted Extensions (8):
* TLSv1.2 (IN), TLS header, Supplemental data (23):
* TLSv1.3 (IN), TLS handshake, Certificate (11):
* TLSv1.2 (IN), TLS header, Supplemental data (23):
* TLSv1.3 (IN), TLS handshake, CERT verify (15):
* TLSv1.2 (IN), TLS header, Supplemental data (23):
* TLSv1.3 (IN), TLS handshake, Finished (20):
* TLSv1.2 (OUT), TLS header, Finished (20):
* TLSv1.3 (OUT), TLS change cipher, Change cipher spec (1):
* TLSv1.2 (OUT), TLS header, Supplemental data (23):
* TLSv1.3 (OUT), TLS handshake, Finished (20):
* SSL connection using TLSv1.3 / TLS_AES_128_GCM_SHA256
* ALPN, server accepted to use h2
* Server certificate:
*  subject: O=Acme
*  start date: Jan 24 16:33:51 2025 GMT
*  expire date: Jan 24 16:33:51 2026 GMT
*  issuer: O=Acme
*  SSL certificate verify result: self-signed certificate (18), continuing anyway.
* Using HTTP2, server supports multiplexing
* Connection state changed (HTTP/2 confirmed)
* Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0
* TLSv1.2 (OUT), TLS header, Supplemental data (23):
* TLSv1.2 (OUT), TLS header, Supplemental data (23):
* TLSv1.2 (OUT), TLS header, Supplemental data (23):
* Server auth using Basic with user 'admin'
* Using Stream ID: 1 (easy handle 0x5b5ace0b8810)
* TLSv1.2 (OUT), TLS header, Supplemental data (23):
> GET /api/v1/actions/rbuilder_restart HTTP/2
> Host: 52.177.21.26:3535
> authorization: Basic <auth>
> user-agent: curl/7.81.0
> accept: */*
> 
* TLSv1.2 (IN), TLS header, Supplemental data (23):
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
* TLSv1.2 (IN), TLS header, Supplemental data (23):
* Connection state changed (MAX_CONCURRENT_STREAMS == 250)!
* TLSv1.2 (OUT), TLS header, Supplemental data (23):
* TLSv1.2 (IN), TLS header, Supplemental data (23):

action definition:

[actions]
...
rbuilder_restart = "/etc/init.d/rbuilder restart"
...

rbuilder service definition: https://github.com/flashbots/meta-evm/blob/main/recipes-nodes/rbuilder/init

But the service actually restarts as seen in the System API logs:

2025-01-28T10:29:01Z 	 [system-api] executing action: rbuilder_restart = /etc/init.d/rbuilder restart
2025-01-28T10:29:01Z 	 Stopping Rust Builder
2025-01-28T10:29:01Z 	 [system-api] executing action success: rbuilder_restart = /etc/init.d/rbuilder restart
2025-01-28T10:29:11Z 	 Starting Rust Builder