Frank Bartes was present during the LHO-Bringuier court case in Aug 1963. However when the FBI questioned Bartes in sept 1963 if he knew of LHO, Bartes told the FBI he never heard of LHO. This was particulary curious as Bartes was an FBI informant.
In the below episodeof The Lone Gunman Podcast at 56 to 57 minutes in, Larry Hancock and David Boylan point out that by around 1963 a lot of people, like Bartes, who were usualy only too happy to inform to the FBI of pro-Castro trouble makers like Oswald, all of a sudden now refused to inform about LHO.
https://www.youtube.com/live/kyo6mkjenfc?t=3377sHancock and Boylan discuss the Tilton Sept 1963 memo which was a CIA memo to the FBI talking about plans to embarrass the FPCC in foreign countries. The impression I took from Hancock and Boylan was that the CIA were possibly planning in Sept 1963 to use Oswalds activities in New Orleans as part of a black propaganda effort in latin American countries. And that perhaps the CIA told people like Bartes in Sept 1963 to stay back from Oswald as a result so that the CIA could use Oswald as part of this propaganda effort in latin American countries. And that this might be why Bartes, despite being an FBI informant and being present during LHOs court appearance, told the FBI in Sept that he never heard of Oswald.
I am doubtful the CIA would have told Bartes to stand back from Oswald in this regard. I dont see how Bartes informing the FBI about LHO could have affected the CIAs propaganda plan as per the Tilton memo.
I think another possibility is that after the Aug 1963 court appearance, both the DRE and INCA were planning their own private propaganda effort against LHO. The DRE were going to write a congressional letter while INCA were going to get a tape made of LHOs media appearance (Arnesto Rodriguez was the one who made the tape as Boylan points out at 57 minutes on the above video). All of these were present at LHOs court appearance so they all knew what each other was doing.
Considering that they were planning their own private propaganda effort against LHO, this may have led to Bartes denying to the FBI the following month that he knew LHO. Bartes may have been concerned that if he gave the FBI any information about LHO that this might in some way scupper their (the DREs and INCAs) planned propaganada operation against LHO. It should also be noted that Orest Pena was connected with this crowd. Pena believed LHO to be an FBI informant and didn't like DeBrueys hanging around with a communist like LHO. We know that Pena at least made Bringuier aware of the LHO-DeBrueys connection as Bringuier stated in a Nov 27th 1963 FBI statment (that Pena had seen LHO at the Pedro restaurant - LINK:
https://www.maryferrell.org/showDoc.html?docId=47745#relPageId=38, which is where Pena alledged LHO and DeBrueys used hang out at). If Pena told Bringuer of how LHO used hang out at the Pedro restaurant, it would be a natural follow on that Pena would have told Bringuier who LHO was in the company of at that restaurant, which Pena later said was LHO. Therefore if Bringuier was aware of this LHO-DeBrueys connection, and knew about this in Aug/Sept 1963, then this information would naturally flow to all the people who accompanied Bringuer to the court appearance including Bartes.
Therefore, the DRE and INCA may have come to see the communist LHO and the FBI as working together in some fashion in the summer of 1963, and for this reason people like Bartes in Sept 1963 might have refused to give any info on LHO to the FBI in case this would scupper the DRE and INCAs planned propaganda operation against LHO (ie the FBI might not have been in favor of such a propaganda effort against one of their informants - LHO).