We are experiencing the same problem with a custom RT1052 board. We have the MCU mapped using the optional 'secondary pinmux' GPIO pins to our QSPI flash memory device (ISSI IS25LP016D-JBLE), which is a 16Mb (2MB) part. We have pull-ups on the boot configuration pins BOOT_CFG[2:0] (GPIO_B0_14:GPIO_B0_12) to set the Flash Type to --- 111b - QSPI device supports 3B read by default (on secondary pinmux option). We are able load the "evkbimxrt1050_flexspi_nor_polling_transfer" example project in RAM and run it. It erases, writes, reads, and verifies the external QSPI flash device on our board. However, we are not able to load our XIP bootable image using the MfgTool (blhost) over the (plain vanilla) UART (without an OpenSDA chip on our board) and receive the following message: "kStatus_FlexSPINOR_SFDP_NotFound", when using the blhost -V -p COM7,115200 -- configure-memory 0x09 0x2000 command. We have tried several QCB (QSPI Configuration Block) option settings with the blhost -V -p COM7,115200 -- fill-memory 0x2000 0x04 0xC0000006; 0xC0000046 ('secondary pinmux' setting); 0xC0000106 (Quad Enable in bit 6 on this device); 0xC0000146, etc. None work.

A similar error is generated when attempting to load the "evkbimxrt1050_led_blinky" image using the MCUXpresso IDE via a LPC-Link2 over the SWJ-DP interface (using SWD). We get this message:

When using the following Project Properties->C/C++ Build->MCU Settings:

Yet, again, when we load and run the "evkbimxrt1050_flexspi_nor_polling_transfer" example project from RAM, everything works as expected.
We are using MCUXpresso IDE v10.3.0 [Build 2200] [2018-12-03] and SDK_2.x_EVKB_IMXRT1050 version 2.4.2, manifest version 3.3.0.
Any help will be greatly appreciated.
Regards and thanks in advance,
-Roger